i might just be completly wrong but here it goes.

so the turbo cat backs are wider than the non turbo. isnt the turbo 3" and the n/a is 2.5". is it possible to use a turbo catback on your n/a and keep the back pressure by making the exhuast pass through 2.5" hole in the 3" pipe. like take this to consideration: i know it wouldnt work like this but if you take a washer that has a hole that is 2.5" wide, but the whole thing is 3". so you weld it on to the end of the cat back(opposite the mufflers).
*********i know that ^^ wouldnt work (with a washer)
wouldnt that create the same amount of back pressure as a 3" pipe. or would the whole thing need to be 2.5" wide. i dont think it would as long as it passes through that 2.5" point.

 

umm......english please!!

 

I kinda got what your saying and i think it should work, aslong as you used a sort of washer like thing that wasnt going to melt and made it think enough it would still create suffecient backpressure in my opinion. Wait till Icemark or one of the other more rx7 knowledgable people reads this and take there opinion. I think it should work, but you never know

 

im almost positive that it would create the same amount of pressure, but would this mess up the cat back system in any way?

 

I guess that would work, the only problem with doing that is that it would make terrible turbulance in the exhaust. I think you might just be better off running 3" exhaust anyways, or get a some pipes that are 2.5" to begin with.

 

yeah, what would be some problems/cons to doing this.....? if it did work.

 

If you had a 3" pipe, the air would be flowing at one rate, then when it hits the washer it will have to abrutly fit through the smaller hole. If you had a 2.5" pipe the whole way there would be no inconsistencies throughout the exhaust, therefore providing better airflow.

 

I think you mean pros/cons. Why would you want to put 3" piping if you are just going to restrict flow? The flow will only be as good as the smallest point it passes through. Even then the flow would be disturbed and create a irregular flow. IMO you should just get 2 1/2" piping that way the flow is more constant.

 

no, i meant problems and cons because i didnt need to know any more pros. but bdoty makes a good point. the reason i wanted to know about this is because i could get a cat back for 250$ and it would be the same as the apex n1, but its for a turbo. the next cheapest thing is 644 dollars (its what im looking at).

are there turbo and non turbo headers? or do all of them fit the same way? because if the 2.5" hole came right after the headers (the very end of the cat back) there would be no inconsistancies (hahah, spelling*)

 

yes, get an adapter from advanced auto and get someone to weld it...works perfectly

 

does anyone know why this wouldnt work?

 

what is this? http://www.racingbeat.com/FRmazda2.htm

is there some sort of flange that connects the headers to the catback with a 2.5" opening?
what if i use a flange for a non turbo catback, but use it on a turbo catback
would that fit?

 

that link didnt work. go to exhuast flanges then click the back pressure flange

 

nevermind then