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  • #16
    Originally posted by CeeP View Post
    Thank you everyone for your responses. I actually started thinking about running the cat last night. If you get a high flow cat, how much does it really hinder the performance of the exhaust? I want to say that it wouldn't be too noticeable.
    I have been wanting to do the exhaust on my 16v for awhile and I have looked into this extensively. It boils down to cfm, obviously, not pipe size. Magnaflow's do not flow as well as other brands. For instance one of the better flowing 2.5" mufflers is a Hooker Max Flow. All other sizes are glasspacks, but the 2.5" Hooker Max Flow is a fully stainless steel straight thru type muffler. It flows 521cfm, which is good for around 250hp. 2.2cfm per horsepower. As far as cats go, buy a Magnaflow Metallic Cat, one with a metal substrate, not rhodium. Offset the cost by recycling your old cats, which are worth at least $75 a piece. This cat flows about 475cfm, and has 300 bricks per cell. So the answer to your question is that the cat flows about 80cfm less than a high flowing 2.5" muffler. Magnaflows mufflers, I have read, flow around 400cfm or less, I have read less but I will be generous. Here are links to what I am talking about:
    Hooker HOK-21614HKR
    http://store.summitracing.com/partde...5&autoview=sku
    Magnaflow 59956
    http://cgi.ebay.com/ebaymotors/Magna...2em118Q2el1247
    My $.02. If you want the Magnaflow muffler, the metal cat will most likely out flow the muffler. BTW, 2.5" straight pipe flows 521 cfm, and crush bent pipe 2.5" flows 417 cfm. Good luck
    1986 Mercedes 190e 2.3-16 Cosworth: http://www.youtube.com/watch?v=-JNJ-qVPBkU

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    • #17
      BTW A1 Exhaust in Santa Ana is supposed to be good. I believe the guy there makes the headers for Turner Motorsports. He wanted $500 for a full Mercedes 2.5" aluminized exhaust if I supplied the cat and the muffler. This was with full madrel bending. I have since decided to keep the 2.25" stock piping and just replace my blown out muffler, but you might want to give this guy a call, his name is Tiger, tell him some BMW guys sent you. Number is (714) 836-7201. Address is 721 S. Main Street, Santa Ana, Ca.
      HTH
      Last edited by project86; 01-18-2008, 09:54 AM.
      1986 Mercedes 190e 2.3-16 Cosworth: http://www.youtube.com/watch?v=-JNJ-qVPBkU

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      • #18
        I have dynoed my car both ways....

        Same exhaust, same everything, but with a high flow Magnaflow cat in place it loses roughly 10 RWHP.

        Not saying you should not run a cat on the street (I do), but it does suck a lot of power out of the S14....

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        • #19
          If I were having a shop do my exhaust I would expect it to cost many hundreds $$$. But, I am lucky in that one of my friends is an excellent fabricator, beyond top notch exhaust fabrication specifically. So by the time I pay for the materials and his time I'll probably get away for well under $500, maybe less than $400. But certainly that is not the norm. This will likely be 3" single pipe all the way back to a free flow muffler (can't recall which one he said he has great luck with). My car is strictly a race car so I won't use a cat but we are considering using some a quick change center piece for a silencer if needed.

          Cheers.
          Jack Money
          '88 M3 #20 DM/GTS2
          Elephant Motorsports Inc

          AST Monotube Adjustable Dampers and Coilover Kits - Full Service Stocking Distributor
          Swift Springs Master Distributor
          JE Pistons Distributor
          Schroth Safety Products Distributor
          Motul Fluids Dealer

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          • #20
            Originally posted by Reelizmpro View Post
            The way I see it, this custom exhaust is going to flow a lot better than the stock exhaust. So I don't think you can lose either way. I'm thinking the difference would be negligible with a large high flow cat.
            a a single 2.5" system provides for a 4% increase overall inner area for flow. My exhaust was rusted out so I needed one and a single system is lighter.

            I installed a cat into my system as I don't have a built motor, and it doesn't move enough air to get effected by the cat significantly. plus, removal of the cat will result in too much flow for a stock engine, if its primarily being driven on the street (if your at high rpm's on the track its a different story). So you'll loose some torque at the bottom end and be loud for a no good reason. Again to clarify. you may lose some hp with a cat but if you look at where that power is, for a person who spends 90% of their time on the street, just put it in.

            put the cat it, it won't hurt and its surprisingly cheaper for a stainless polished highflow cat then it is for a muffler.
            Last edited by paintpro21; 01-18-2008, 03:55 PM.
            ApexRaceParts.com - Facebook Fan Page - Twitter

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            • #21
              Are you speaking from experience or intuition? I don't think removing your cat from an otherwise stock engine will cause a loss of torque. But I'm speaking from intuition. I've not tested this myself.

              Jake

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              • #22
                I just built an exhaust for my s50 swapped 318 and I gotta say, I can't believe you can build a SS exhaust with nice components for $1000. I bought an AA track pipe (just the front piece) and then went on to build a single SS 2.5" exhaust with a magnaflow cat and muffler. Both high flow, universal pieces. I spent about $500 on exhaust piping, magnaflow parts, flanges and hangers. I did all the work myself which is the only way it worked out financially for me. I bought a few pre-mandrel bent section to cut up and splice into the system and that worked very well. it's not a perfect system but it has good components, good workmanship and it's all SS.

                Paintpro may be the standout for finding a good deal on fabrication but I think he got lucky. It's hard to find a shop to do all that labor for so cheap, especially if you want a nicely built exhaust. If I could have a 2.5" system built for the m3 I would think that is a good decent price. Especially when you price shop out your options. Think of how much a VSR center section and Borla muffler costs...about $1200 without shipping install hassles.

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                • #23
                  I agree !

                  I just had a custom exhaust fabricated. The Burns x-pipe was $ 400, the Magnaflow muffler was $ 100, and the actual dual two inch exhaust was $ 900. I had a one man shop that usually only does NASCAR headers do the work. He does not bend anything, uses only Burns stainless pipe. Total for the project was over $ 1400 USD but it is very nice.

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                  • #24
                    Guys,

                    When we're discussing the generic term 'stainless steel', let's also include what type. There are several and the costs vary. We can't compare total costs without that info. We also need to know weld type. Bend type is also important to total cost.

                    If someone says they just built an inexpensive system 'with SS' I'd assume they used 409 SS unless otherwise stated b/c it's the least expensive of the common SS piping. I'd also assume it was MIG welded.

                    As others have claimed, building a custom system can be done w/o spending 'lots of money', but it will likely have to be aluminized (maybe 409), crush bent and MIG welded. Money can be 'saved' by just installing a muffler, but I think most of those systems will be overly loud and the owners unhappy in the long run. (I'll leave out the emissions rant this time.) Additionally, these systems will rust to some degree and not flow as well as a 304 (or better) TIG welded, mandrel bent system. This is where people like to say "you get what you pay for." That last X% of performance is always very expensive.

                    Project86 - Can you point us to where the Magnaflow and Hooker product(s) were tested? I'm going to need some convincing beyond the little marketing blurb on Summit's site. I think all straight-through designs are all going to flow virtually identically. Additionally, a 14" box is going to be very loud. And what about the part that says 'for engines with c/r 8.5:1 and lower'. A bone stock S14 is 10.5:1.

                    -Dietrich

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                    • #25
                      Originally posted by Dietrich View Post
                      Guys,

                      When we're discussing the generic term 'stainless steel', let's also include what type. There are several and the costs vary. We can't compare total costs without that info. We also need to know weld type. Bend type is also important to total cost.

                      If someone says they just built an inexpensive system 'with SS' I'd assume they used 409 SS unless otherwise stated b/c it's the least expensive of the common SS piping. I'd also assume it was MIG welded.

                      As others have claimed, building a custom system can be done w/o spending 'lots of money', but it will likely have to be aluminized (maybe 409), crush bent and MIG welded. Money can be 'saved' by just installing a muffler, but I think most of those systems will be overly loud and the owners unhappy in the long run. (I'll leave out the emissions rant this time.) Additionally, these systems will rust to some degree and not flow as well as a 304 (or better) TIG welded, mandrel bent system. This is where people like to say "you get what you pay for." That last X% of performance is always very expensive.

                      Project86 - Can you point us to where the Magnaflow and Hooker product(s) were tested? I'm going to need some convincing beyond the little marketing blurb on Summit's site. I think all straight-through designs are all going to flow virtually identically. Additionally, a 14" box is going to be very loud. And what about the part that says 'for engines with c/r 8.5:1 and lower'. A bone stock S14 is 10.5:1.

                      -Dietrich
                      I found this stuff all on the web. Here is the cut and copy:
                      All tests via an independent lab
                      All tests @ 15 wc

                      2 Straight Pipe 283 CFM
                      2 Straight Pipe 365 CFM
                      2 Straight Pipe 521 CFM

                      2 Typical Bent tailpipe 268 CFM
                      2 Typical Bent Tailpipe 417 CFM

                      2 Inlet/Outlet_ Glass Pack Tips- No Louvers- Smooth 274 CFM
                      2 Inlet/Outlet- Glass Pack Tips-Louvered 133 CFM
                      Same as above set for reverse flow 141 CFM
                      2 Cherry Bomb 239 CFM
                      2 Cherry Bomb 294 CFM

                      2 Inlet/Outlet Dynomax Super Turbo 278 CFM
                      2 Inlet/Outlet Ultraflow Bullet 512 CFM
                      2 Inlet/Outlet Gibson Superflow 267 CFM
                      2 Inlet/Outlet Flowmaster ( 2 Chamber) 249 CFM
                      2 Inlet Outlet Flowmaster ( 3 Chamber) 229 CFM
                      2 Inlet/Outlet Thrush CVX 260 CFM
                      2 Inlet/Outlet Maremount Cherry Bomb 298 CFM
                      2 Inlet/Outlet Hooker Aero Chamber 324 CFM
                      2 Inlet/Outlet Hooker Max Flow 521 CFM
                      2 Inlet/Outlet Borla Turbo 373 CFM
                      2 1/2" Inlet/Outlet Magnaflow 284 CFM


                      Standard OEM 2 Inlet/Outlet 138-152 CFM
                      Standard OEM 2 Inlet/Outlet 161-197 CFM
                      Here is the link, I am not sure where it originated from:
                      http://www.moddedmustangs.com/forums...ufflers-2.html
                      1986 Mercedes 190e 2.3-16 Cosworth: http://www.youtube.com/watch?v=-JNJ-qVPBkU

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                      • #26
                        Lots of good information on here guys, thanks.
                        Another question though, what are you guys using for tips?
                        I just checked my bumper and it looks like dual 3" would be a real tight fit.
                        Dual 2.5" looks like it would be a better option.
                        Also, are you having your shop fabricate them or buying them somewhere online.

                        "Unlike the latter day E36 and E46 M3's, the
                        original E30 M3s main purpose in life was to
                        win races on the track, not the street. It
                        got the job done."

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                        • #27
                          I started with a muffler with dual tips, but it (muffler) was too small and louder than hell.....

                          I finally went with a huge single 3" in/out Magnaflow muffler. It is adequately quiet. Unless you really like loud cars, I don't think you will find a twin pipe muffler that is large enough.

                          I just had them "ovalize" the tailpipe out the back to sorta fit the cutout, and called it good.

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                          • #28
                            From what I've gathered it seems the Hooker Maxflow is essentially a quiet straight pipe, the best of both worlds. However, the HP numbers in that same test only show a 1HP difference between it and the Magnaflow although outflowing it by 200 CFM or so. I'm curious what the rest of the curve looks like between the two. Sounds like a good product and it's cheap!

                            88 M3 - LACHSSILBER/M TECH
                            89 M3 - ALPINEWEISS II/SCHWARZ
                            85 323I S52 - ALPINEWEISS/SCHWARZ
                            91 M TECHNIC TURBO - MACAOBLAU/M TECH


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                            • #29
                              Richard's Performance Muffler in Vista did my work for me using Lee's flange.
                              http://www.rpmmuffler.com/
                              They do very good work there.
                              Michael
                              www.purems.com | Temecula, CA | 866-397-5487

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                              • #30
                                :tiny:Looks like I gotta pick up a Hooker! Oh yeah I took my catalytic off a few weeks ago... definitely feel more torque & hp but a little loud.
                                Last edited by ///schwartzman; 01-19-2008, 05:34 PM.
                                Rich!

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