3" catback questions

[jeffmsp]

hey all,

well first I got the wrong size piping when i first did the exhaust, it was a 2.25" midpipe with a 2.5" highflowcat. So i finnally got around to fixing it. The way my midpipe works is there is a 5 inch long 2.25" section coming from the downpipe to where the cat is. From the cat all the way back to the axle back flange is 3" SS. Once again I feel very little in the ways of power increase, there may not even be any at all (scratch) very little sound increase too. Do you guys think it dropped the backpressure much or should i wait until i the RRE downpipes are made before turning up the boost a bit more(like 1psi increase)? Did anybody who put a catback on feel any power increase at all? Do you think that since i still have the stock axle back portion that i am not seeing any gains?

Also, even with hardpipes and the exhaust i still cannot hold over 7psi at redline....(spike to 10 around 3-4k)any thoughts on why that is? The car has no top end pull, its like it gets tired after 5.5k.

[Dr.Sound]

with a 2.5 catless downpipe and stock rear section i could not hold steady boost to redline.

now i have 2.5 from s-pipe back, with hi-flow cat and nice straight-through muffler.
boost holds to redline.



3"......?
dont know man, turbo cars need backpressure.
i've spoken to many tuners, young and old, and they all said that 2.5 is perfect for our cars.
i guess if u see 300 hp in your future then 3" is cool.

your problem might also be because your pipes are inconsistent.

[jeffmsp]

if i can get one of those rre 2.5" dps then it will mate nicely with the cat and then 3" after that, i figured a 3inch downpipe was overkill.

[Dr.Sound]

if i can get one of those rre 2.5" dps then it will mate nicely with the cat and then 3" after that, i figured a 3inch downpipe was overkill.yeah, that should be good.
and if u want good sound, i recommend Tsudo Titanium tip Carbon Fibre muffler.
to date i havent heard anything better sounding on MSP.

[jeffmsp]

yeah, a nice sounding muffler would be great!, but for now i am sticking with function over form, at least until i can back up a loud muffler with some hp. Do you have a clip? I could use it to finish off the system once the dp is here.

[krillin]

huh? mine?




yeah, that should be good.
and if u want good sound, i recommend Tsudo Titanium tip Carbon Fibre muffler.
to date i havent heard anything better sounding on MSP.

[Dr.Sound]

hey monkey!
how've u been?!?!

i like yours, but i like tsudo better.
it's deeper.

[goku4658]

3"......?
dont know man, turbo cars need backpressure.
i've spoken to many tuners, young and old, and they all said that 2.5 is perfect for our cars.
i guess if u see 300 hp in your future then 3" is cool.

So you're anti Ion's 3" turbo back?

[Dr.Sound]

i will not say that i'm a car tunning guru.
so i will not say that for sure i know 2.5" is better than 3" for our cars, BUT, i've spoken to car gurus. and they told me that the gains from 2.5 to 3 will be minimal.

[mazdaowner123]

I've always heard turbo cars do not want back pressure. This makes sense because you want as much exhaust gas going through the turbo as possible. For our small turbo at stock or close to stock boost, you probably will be fine with 2.5".

Anyway, part of your lack of power gain could be the fact that you're running 2.25" piping. That's pretty small, you might wanna make that 2.5".

~brian

[jeffmsp]

if i can get the dp from rre it will be 2.5" to the cat. The 2.25" section is not long at all.

[Dr.Sound]

it doesnt really matter how long it is.....
if it's there, it will slow down the flow.

[thunder]

I put a 2.5'' midpipe (kept the 'J' pipe for now) w/Magnaflow Cat and I felt a noticable difference... I'd say prolly around 10 HP and way better spool. I don't know why it didn't work for you (maybe the Cat?)...


hey all,

well first I got the wrong size piping when i first did the exhaust, it was a 2.25" midpipe with a 2.5" highflowcat. So i finnally got around to fixing it. The way my midpipe works is there is a 5 inch long 2.25" section coming from the downpipe to where the cat is. From the cat all the way back to the axle back flange is 3" SS. Once again I feel very little in the ways of power increase, there may not even be any at all (scratch) very little sound increase too. Do you guys think it dropped the backpressure much or should i wait until i the RRE downpipes are made before turning up the boost a bit more(like 1psi increase)? Did anybody who put a catback on feel any power increase at all? Do you think that since i still have the stock axle back portion that i am not seeing any gains?

Also, even with hardpipes and the exhaust i still cannot hold over 7psi at redline....(spike to 10 around 3-4k)any thoughts on why that is? The car has no top end pull, its like it gets tired after 5.5k.

[jeffmsp]

the cat is 2.5" highflow SS. Came with a 3 year warranty 2 (2thumbs)

I think it must be the 2.25" piping and the placement of the cat. The cat sits very close to the J pipe in comparision to other midpipes like apexi etc. The 2.25" section is too small i think to build up enough flow before hitting the cat, i think thats whats slowing it down...thenagain i really have no idea what i am talking about, just trying to figure it out lol Come on RRE DPs!