Exhaust Size W Forced Induction?

90lxwhite

I'm kind of a She-Man
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Aug 25, 2011
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Alright fellas here's the deal: I recently installed a Vortech si and I'm wondering much things on the exhaust end are holding me back if any? My setup is as follows. 302 w slightly "worked" e7's w beehive springs, .512 lift on in and ex, stock ho upper intake with ported lower, stock headers, stock h pipe w pre cats removed, the other's were replaced with high flows, and Forzaflow mufflers. Before the blower I was making 223 rwhp and I think like 280 some odd ft lbs. (waiting for tune appt) Since I'm forcing more air in do I need to step up to 2.5 or with my modest combo will the 2.25" suffice? I'm guessing that there would be no real gain if I went catback only. If I indeed should go 2.5" what's the best way going about doing it? Get a 2.5" mid pipe(I want cats due to smell) and a 2.5" catback system? Or is it more cost effective to purchase a 2.5" header back weld-up system? Or how a about having a shop fab up something custom? Labor costs is a factor if that will help narrow down the decision. Oh and no "long tubes ftw" please, ain't happenin'. One more question if I go w larger piping are the chances fairly great that I'll have to get new mufflers?
 
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I think you'll need new mufflers if you increase exhaust pipe diameter.

I feel since you're still on E7's and mostly stock everything, 2.25" will suffice for what you want from it. Each 2.25" is dealing with a ~170hp 2.5 liter 4 cylinder, in essence, (assuming you make 300rwhp with the blower). Less restriction is more power, don't get me wrong.. I just don't feel that with your combo you're aiming for maximizing power anyway.
 
I think you'll need new mufflers if you increase exhaust pipe diameter.

I feel since you're still on E7's and mostly stock everything, 2.25" will suffice for what you want from it. Each 2.25" is dealing with a ~170hp 2.5 liter 4 cylinder, in essence, (assuming you make 300rwhp with the blower). Less restriction is more power, don't get me wrong.. I just don't feel that with your combo you're aiming for maximizing power anyway.
honestly if I'm looking at an arm and a leg for 5 or 6 extra horsepower I'd leave it as is but for say I dunno 20 or so horse it'd be worth considering.
 
Pick yourself up a set of used 1 5/8" shorty headers, and a 2 1/2" off road mid pipe and call it a day. You could probably get it done for a couple hundred bux.

The stock 2 1/4" diameter exhaust will support over 375fwhp. No need to go bigger...especially if you've already got a set of hose knock off Flowmasters on there.

Since you're running that blower, I'm betting with the stock headers on there and bastardized H-pipe you're probably leaving a good 10-12hp on the table....maybe more?

Stepping up to a 2.5" cat back at this point without addressing the other issues is likely just going to make your car louder. The cat back isn't the cork....the headers and mid pipe are.
 
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Pick yourself up a set of used 1 5/8" shorty headers, and a 2 1/2" off road mid pipe and call it a day. You could probably get it done for a couple hundred bux.

The stock 2 1/4" diameter exhaust will support over 375fwhp. No need to go bigger...especially if you've already got a set of hose knock off Flowmasters on there.

Since you're running that blower, I'm betting with the stock headers on there and bastardized H-pipe you're probably leaving a good 10-12hp on the table....maybe more?

Stepping up to a 2.5" cat back at this point without addressing the other issues is likely just going to make your car louder. The cat back isn't the cork....the headers and mid pipe are.
Could not agree more with this post. Didn't feel that "liking" the post was good enough. Headers and h pipe are your problem. Used parts could easily fix the problem for you for under $300. (Depending on the area you live and market). You could do it for under $200 provided you are willing to go off road h pipe.
 
Could not agree more with this post. Didn't feel that "liking" the post was good enough. Headers and h pipe are your problem. Used parts could easily fix the problem for you for under $300. (Depending on the area you live and market). You could do it for under $200 provided you are willing to go off road h pipe.
I haven't looked yet but I bet the biggest obstacle w going used is finding '95 specific headers to where I wouldn't have to do sum riggin w the egr n crap. Y'all know the thread post pics of how y'all's fox sits, well there are like 2k replies. I tried to post a lets see sum sn's and got 13 replies.
 
Yesterday (on craigslist) I just sold a used set of 1 5/8" MAC equal length headers for $50, a 2.5" offroad Bassani X pipe w/ flowmaster 40's for $100 and not too long ago a 2.5" BBK h-pipe with cats for $200. This weekend i'm basically giving a stock long block away with a set of 1 5/8" JBA unequal shorties for free (the guy has to yank motor himself and hand me the trans, clutch and flex plate). He will do this in my garage.

The good deals are out there and I'm one to give them. My advice is upgrade to 1 5/8 unequal length shorty headers, 2.5" h/x pipe. Don't cut yourself short on this and search for the good deals.
 
I put 6 exhaust systems on my car and 5 of them went on the dyno. Long tubes made noticeable HP numbers over shorties and made double digit TQ numbers in every RPM over them. They are worth it. I should have went this route from day 1.
 
I put 6 exhaust systems on my car and 5 of them went on the dyno. Long tubes made noticeable HP numbers over shorties and made double digit TQ numbers in every RPM over them. They are worth it. I should have went this route from day 1.

Nobody can really argue the HP difference between long and short headers it's just that the OP made it clear he doesn't want to go that route so it's really a non-point.

I just got my 1 5/8" ceramic coated BBK longtubes and h-pipe from LMR and can't wait for the day I get to install them.