I really didnt want to remove my Borla catback but it all depends. I have a RR header that came with the motor that Mazdaspeed7 had built . I jsut bought it from the guy he sold it too.



anyhow, can I get a flange and a collector and have it welded to my catback or MUST I keep it dual all the way out the rear?



I have a buddy who owns an exhaust shop and he can do it either way. what I need to know is what way is going to work the best for a stock motor and or a large ported engine like the one I just got?



I want it to work one regardless of the current Borla catback so if I must I will remove the Y pipe section and just use the Borla mufflers. my goal is to not hack up my lifetime warranty Borla exhaust system .



I want to use the header on car right now till motor is pulled out and bridge ported motor is put in.



I will be using stock S5 intake for a while at least .

I think that is all the info.



I searched and after 45 threads I got tired of reading.





thanks

 

buy the road racing header flange from racing beat , cut the single pipe portion of the mid pipe and cat back exhaust and run a true dual exhaust. the power gain is well worth it and since the intention is a bridge port motor that is the only way to go anyways, if you run the road race header to a colecter you may not optimize the true potencial of that header.

thats my 2 cents and that came from trial and error in the past with a s3 a customer of mine has.

 

ISC has a mid pipe that attaches to the dual outlet header. It's a 3" outlet. Might give you some ideas anyway.



A collected system, when done correctly will give you more power than an uncollected system. Without a collector you are not taking advantage of scavanging. The collector needs to be in the right spot but it's well worth it.

 

what/ who is ISC?



so where does the collector need to be to work right? I thought it would be where the header ends..





































[quote name='C. Ludwig' date='Mar 27 2005, 04:21 AM']

ISC has a mid pipe that attaches to the dual outlet header. It's a 3" outlet. Might give you some ideas anyway.



A collected system, when done correctly will give you more power than an uncollected system. Without a collector you are not taking advantage of scavanging. The collector needs to be in the right spot but it's well worth it.


[/quote]

 

www.iscracing.net



They're a race prep shop in Winter Haven, FL.



Without going in to a long winded diatribe, the collector can be in various different places and where it's located is dependent on your engines power characteristics. An engine with it's peak power built at a higher RPM will want a a header with a shorter primary (has the collector closer to the engine). So a P-port motor will have a shorter primary than a stock port motor. There is a formula you can use to determine where to place the collector.



Now there are short and long primary systems. Again without going in to the details, that I might now explain correctly, a short primary system is setup to take advantage of the first order of scavenging only while a long primary system can take advantage of 4th order scavenging. This better and will produce the same peak power while giving a broader torque curve. The problem is long primary systems have primary lengths in the 80-120" range so packaging becomes difficult.



Here is a link that has excellent info on the subject as well as a simple formula to determine primary length of any engine for which you know where peak power occurs. Clicky-Clicky



When I posted the pic of the ISC system I didn't mean to state that was THE system you should use and it would be perfect for you engine combination. It was meant to give you an idea and show you how some guys are working with the dual outlet header.

 

A collected system will give slightly better performance only if tuned perfectly to your motor.

A dual system typically gives more low end torque, gives up little at the top, and does not have to be tuned..



I personally like the stereo growl of a true dual in a 2nd gear pull to 70.



This link is to a video of my almost stock NA with a full dual.

link to a short video