Has anyone gone 3" d/p ------> 2.5" cat..

[All Boost]

Has anyone went with a 3" downpipe and 2.5" cat back? I'm getting a d/p and catback but keeping the stock muffer. (I don't want loud at all, just sube sounding) I was thinking if the downpipe with a HIFLOW cat was too loud, maybe i'd put a magniflow resonator on.

Anyone have this situation? I think its going to be a hard fit making the cat back fit the stock muffler since its smaller.

[wicked]

you do realize the stock muffler is very restricting?and only 2.25 dia.
kinda defeats the purpose of the over-sized down pipe.
but hay,do what you want

[Heathen23]

you do realize the stock muffler is very restricting?and only 2.25 dia.
kinda defeats the purpose of the over-sized down pipe.
but hay,do what you want
Stock muffler isn't that restrictive. It's a straight through design so it's not all that restrictive for a stock muffler.

[wicked]

Stock muffler isn't that restrictive. It's a straight through design so it's not all that restrictive for a stock muffler.it's not restrictive when compared to most other stock units(i.e. honda,nissan,dodge....)

[All Boost]

you do realize the stock muffler is very restricting?and only 2.25 dia.
kinda defeats the purpose of the over-sized down pipe.
but hay,do what you want
The last thing i want is for my car to sound like my old civic with a vibrant exhaust.

Like Heathen23 said, it is a straight through muff. And people with just downpipes are seeing huge gains because the closer you get to the turbo the hotter the gases are, and the big DP would allow more room for exhaust gases to expand.

Hopefully i can find a balance for HI HP gains and minimal sound.

[WillisW555]

How small is a stock honda exhaust? I swear the one on a civic is no bigger than 2", although I haven't measured it. The muffler tip in itself is like 1 1/2" of something like that.

[YellowSpeed17]

All Boost-I have a APEX 3" catless downpipe with a JIC 60mm(2.4") cat-back exhaust and it sounds awesome. Sounds like a WRX up to about 3000 rpm and after that it gets pretty loud but sounds real deep and not like a Civic or Integra. I get compliments all the time on how it sounds and people always say they like it because it doesn't sound like a Honda.

[All Boost]

Nice, i'm supprised that with a catless system you still get a deep sound. I'm in the process of building it now, i don't think its going to be that hard, i am looking for the O2 sensor bung now, i'll prolly find one at a exhaust shop.

Yellow speed. Did you have any trouble mating flanges? from the 3" to 2.5 or the 2.5 to stock?

[All Boost]

Oh ya, i've heard some mixed things about Cats now. I'm not sure which to buy, some people say the maniflow ones burn out after a year. that doesn't sound right to me.

Any one know which cat is best for the buck? I'm lookin to spend only 150-200 Canadian

[Heathen23]

Nice, i'm supprised that with a catless system you still get a deep sound. I'm in the process of building it now, i don't think its going to be that hard, i am looking for the O2 sensor bung now, i'll prolly find one at a exhaust shop.

Yellow speed. Did you have any trouble mating flanges? from the 3" to 2.5 or the 2.5 to stock?
The turbo smooths out the sound. It would seem pretty hard to make a turbo car sound like a a pack of humping bumble bees.

[YellowSpeed17]

All Boost-Nope. The flanges fit perfectly.

[goku4658]

what makes more sense? from downpipe to catback...going 2.5 to 3? or 3 to 2.5? i'm tryin to figure out what plan of attack to go with on my exhaust. thanks!

[FSDET]

3----> 2.5 for sure

[Heathen23]

3----> 2.5 for sure
How the heck does going from flow source 3 to outlet 2.5 make sense?

I'm gonna go out on a limb and say smaller to larger makes more sense.

[goku4658]

what effect would temperature have on the setups? like would it be better to have the 2.5 to 3, cuz the air is hotter in the downpipe and therefore would move faster and then into a 3inch catback?

[WillisW555]

You can try to have a cutout put on your DP. That's what some people are trying to do... a few have done it. Then you can bypass the exhaust completely if you want to.

[All Boost]

I'd say you want the 3" dp and 2.5 cat back. The bigger d/p will allow more gas to flow while its hot. when it cools, it doesn't need as much space to go fast.

It makes sense. Thats the reason people with JUST D/Ps on have good gains.

peas

[wicked]

(just my 2 cents)
I recomend you go three inch all the way (catless)but keep it quiet by using a good muffler and maybe 2 resanators,the ones that www.modernperformance.com (http://www.modernperformance.com/) has worked very,very well for me. I agree that the quieter the better.but if your doing your exhaust do it right.
a freind of mine has these resanators and a megan muffler on his 2.0 turbo focus
and it sounds like a bmw m3,it's way under 95 decibals
good luck

[MP3skaterNC]

why would you want to create a bottle neck like that? Just go 2.5" the whole way, or 3" the whole way. Having many changes in diameter is going to be pretty restrictive.

[All Boost]

True say, I was basing my decision on downpipe availablility and price. I found IONs 2.5" with HI-Flow cat. I'm going with that one.

Then a 2.5 custom cat back with a magniflow resonator. Stock muff. I think that should sound pretty good. Deep but not loud. I'm lookin to hear it only when i'm wide open.

[on point]

again, what is the best aftermarket cat to buy?

[iON Performance]

on point (http://www.msprotege.com/forum/member.php?u=9146) - it depends on your idea of "best". Our hi-flow cats utilize German catalyst cores which are highly efficient (same ones used by RUF, Brabus etc). We've found that the ones we use flow equally as much if not slightly more then the equivalent sized Random Tech.