2.5" vs 3.0" exhaust

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2.5 or 3" exhaust?

better
9
90%
junker
1
10%
doesn't matter
0
No votes
 
Total votes : 10

2.5" vs 3.0" exhaust

Postby theUNYTEDone » Sun Jul 09, 2006 9:58 am

which would you see as better on an ST185 with roughly 325 ish AWHP?

and why.

reason for the thread is i get a lot of crap for going to a 3 inch open (no cats) system. wondering if the switch back after my car's done will be worth it. the HP number up there will be about what i'm running...thanks guys!
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Postby OlyST185 » Sun Jul 09, 2006 1:22 pm

3inch all the way.
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Postby TheAutoholic » Sun Jul 09, 2006 2:18 pm

This is a silly question. Turbo cars neeeeed to breathe.
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Postby Mafix » Sun Jul 09, 2006 3:04 pm

3" baby!!
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Postby grip addict » Sun Jul 09, 2006 3:07 pm

i need to warn everyone-
ATSAaron wrote:You specifically told Matt that "some kid dumped sand into my motor."

don't let some kid dump sand into your motor.
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Postby Simba » Sun Jul 09, 2006 3:20 pm

I've run both. 2.5" not only fits better and has much more room to move through the rear suspension, but flows just as well as 3" at that power level.

Also, most 3" exhausts are misleading, as they have sections that are crunched well under 3". When I made my 2.5", I used normal mandrel pieces and didn't have to tweak or crunch anything.

Lots of fast, loud things.
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Postby ChrisD » Sun Jul 09, 2006 3:58 pm

I have a 2.5" downpipe and 3" mandrel bent for the rest. There would probably be some power available at the 325 whp level, but you'd gain a few things in terms of noise, ease of fit, etc.

It's up to you. i would bet there would be a small penalty to running the smaller size. That said, I make plenty of power with a 2.5" dp.
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Postby MetalliKAT97 » Sun Jul 09, 2006 4:03 pm

grip addict wrote:open dp

http://www.aussie-speed.com/faq.htm


lack of backpressure?...tried it....SUCKED :P
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Postby gearhead313 » Sun Jul 09, 2006 4:11 pm

I've also run both. Though I dont know my hp numbers, I can tell you that after going down to 2.5", it was disapointing. The torque felt the same, aka 5th gear, putting up hills, etc... but the power through the top end is what I lost. It kinda pisses me off, but i'm dealing with it. The 2.5" is definitly more DD friendly :oops:
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Postby Fraggle » Sun Jul 09, 2006 4:54 pm

MetalliKAT97 wrote:
grip addict wrote:open dp

http://www.aussie-speed.com/faq.htm


lack of backpressure?...tried it....SUCKED :P


i agree, my car ran like absolut crap when i was open dp
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Postby Conan » Sun Jul 09, 2006 5:23 pm

2.5 will become a restriction for 325 HP, which is around 400 flywheel. Go for full 3 inch.
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Postby celicat93 » Sun Jul 09, 2006 5:31 pm

your poll needs some tweaking. You ask 2.5" or 3", but then your poll responses are "better" and "junker". Which is better and which is junker? The questions should just be 2.5 and 3 I've heard the arguments go both ways, and before investing myself, I'd like to see the numbers from people who've done it.
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Postby gearhead313 » Sun Jul 09, 2006 7:11 pm

Fraggle wrote:
MetalliKAT97 wrote:
grip addict wrote:open dp

http://www.aussie-speed.com/faq.htm


lack of backpressure?...tried it....SUCKED :P


i agree, my car ran like absolut crap when i was open dp




really?? I took mine for a ride open DP when I was working on the exhaust and it pulled WAY harder than with the exhaust on it.
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Postby toayoztan » Sun Jul 09, 2006 7:53 pm

celicat93 wrote:your poll needs some tweaking. You ask 2.5" or 3", but then your poll responses are "better" and "junker". Which is better and which is junker? The questions should just be 2.5 and 3 I've heard the arguments go both ways, and before investing myself, I'd like to see the numbers from people who've done it.


+1

I don't know how to answer your poll..... :shrug:

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Postby theUNYTEDone » Sun Jul 09, 2006 8:42 pm

:doh: thanks for tha poll input, guys. i guess i had the 3" system in mind when i slapped it together. forgive me, it was 130 in the AM....as for your replies, i'm currently running the 3" now, and was just wondering about it in the future, there's ALWAYS argument on the benefit-s and drawbacks of both systems...but, GREAT! keep the replies coming. :D

what the hell, how do you edit the poll?
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