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-   -   WTB AFtermarket Midpipe (https://www.seccs.org/forums/showthread.php?t=7543)

02STI 2009-03-25 08:05 AM

Quote:

Originally Posted by 100_Percent_Juice (Post 130474)
might need to go ...gulp... custom.

:huh: custom,,what is that :?: naw jk. idk. i guess i might have to.. or maybe i should keep the stock catback..

cody 2009-03-25 08:25 AM

Does your DP have a 3" flange or the OEM style donut gasket?

If it's the donut style, http://www.daddysscp.com/dcart4/prod...&cat=17&page=1

3" flat flange: http://www.daddysscp.com/dcart4/prod...&cat=17&page=1

cody 2009-03-25 08:34 AM

Quote:

Originally Posted by Kevin M (Post 130472)
If you're keeping a 2.5" axleback, you don't need a 3" midpipe.

I was thinking the same thing. But at some powerlevel there's theoretically a benefit but the only evidence I have to support that is the fact that the TurboXS Stealth Back is a TBE that replaces everything except the stock muffler. For a stage two 2.0L, for example, the muffler doesn't seem to be a big restriciton (although it does hold back probably 5HP)...but you'd think that the muffler would be a bigger restriciton than a straight pipe given that the muffler isn't straight through like the pipe. Dunno.

The gasses cool and contract as they travel down the TBE. Larger pipes offer less performance benefit toward the exit end of the exhaust tract (the muffler) than they do toward the hot side.

02STI 2009-03-25 10:05 AM

cool. thanks for the links, yea, i just wantet to have the 3" midpipe so it could be alittle bit more flow, i have the sti catback, if thats on the sti its good for me, but i just wanna keep the axle back not the stock midpipe, idk if it will add any power, im sure it wont but still..

cody 2009-03-25 10:30 AM

My CBE is really overkill since I'm essentially just stage II on a 2L. I have a ceramic coated DWG shorty DP to 3" ID all the way, straight through with one high-flow cat in the midpipe. All I'd need to go to a bigger turbo is injectors, TMIC, the snail, a tune and a tranny fund. :unamused:

02STI 2009-03-25 10:39 AM

yea lol.. you need to get new exhaust, i have 4" DP on top and goes to 3" and sti catback, catless ;) i recently changed my turbo, injectors, ecu, TM :D

cody 2009-03-25 10:43 AM

I don't need a new exhaust, but it sounds like that STi CBE might be a serious restriction if you've got a significant turbo upgrade.

Kevin M 2009-03-25 12:26 PM

Quote:

Originally Posted by cody (Post 130491)
I was thinking the same thing. But at some powerlevel there's theoretically a benefit but the only evidence I have to support that is the fact that the TurboXS Stealth Back is a TBE that replaces everything except the stock muffler. For a stage two 2.0L, for example, the muffler doesn't seem to be a big restriciton (although it does hold back probably 5HP)...but you'd think that the muffler would be a bigger restriciton than a straight pipe given that the muffler isn't straight through like the pipe. Dunno.

The gasses cool and contract as they travel down the TBE. Larger pipes offer less performance benefit toward the exit end of the exhaust tract (the muffler) than they do toward the hot side.

That whole thing is a myth. It's based the Ideal Gas Law, PV=nRT, except for one slight flaw- IGL deals with closed systems. If you keep your axleback, there is no benefit to replacing your midpipe.

Kevin M 2009-03-25 12:27 PM

Quote:

Originally Posted by 100_Percent_Juice (Post 130474)
might need to go ...gulp... custom.

Why?

100_Percent_Juice 2009-03-25 12:41 PM

If he is going from a 3" DP to a 2.5" axle back then he would need a mid pipe like the one in Cody's link.

cody 2009-03-25 01:17 PM

Quote:

Originally Posted by Kevin M (Post 130507)
That whole thing is a myth. It's based the Ideal Gas Law, PV=nRT, except for one slight flaw- IGL deals with closed systems. If you keep your axleback, there is no benefit to replacing your midpipe.

So you're saying that a bottleneck midpipe isn't any different than a bottleneck before/in the muffler, for example? Interesting. Do you have a source you could link me to?

Kevin M 2009-03-25 01:46 PM

Quote:

Originally Posted by 100_Percent_Juice (Post 130509)
If he is going from a 3" DP to a 2.5" axle back then he would need a mid pipe like the one in Cody's link.

NT RLY. Unless it's flat flange and just plain won't seal to his stock mid.

Kevin M 2009-03-25 01:49 PM

Quote:

Originally Posted by cody (Post 130513)
So you're saying that a bottleneck midpipe isn't any different than a bottleneck before/in the muffler, for example? Interesting. Do you have a source you could link me to?

Link? No. Just think about it. How is moving the obstruction 30" downstream affecting anything? The gains in that old TXS setup come entirely from the downpipe, because the stock downpipe flange is a much bigger restriction than the piping size of stock exhaust. But once that's gone, if you don't upgrade all the pipe sizing you don't get much compared to replacing all of it.

100_Percent_Juice 2009-03-25 04:35 PM

Quote:

Originally Posted by Kevin M (Post 130514)
NT RLY. Unless it's flat flange and just plain won't seal to his stock mid.

I don't understand your post.

02STI 2009-03-25 04:52 PM

I don't understand anything anymore :?:

sedonabugeye 2009-03-25 10:57 PM

adolfo.. sack up and go custom!!!!! haha!

02STI 2009-03-26 08:41 AM

Quote:

Originally Posted by sedonabugeye (Post 130566)
adolfo.. sack up and go custom!!!!! haha!

hahaha.. i think im just gonna try to get an Apex catback, they sound nice.

dayofpain 2009-03-26 03:10 PM

tanabe midpipe. no cats no resonators.

100 bucks avail right now!!!


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