will a 2.5" section in my 3" exhaust matter much?

[DevilSperm]

reason i ask is im making a full 3" next week and i have a 2.5" test pipe..i thought i could just use it to connect to the downpipe and then go back from there...but i didnt know if that little 1 foot section would be too restrictive....just need opionions please

 

[gsxeclipseguy]

i wouldnt think so...if it fits there shouldnt be much difference than with a 3in pipe. find a ruler and look at half and inch....not that big so it cant be that bad. I dont think there would be any noticible difference and its better than having a cat.

 

[mrb91gsx]

As long as your exhaust doesnt go from 3" to 2.5" back up to 3" you wont have an issue.

 

[DevilSperm]

well it would, i was planning on a 3" DP, led to the 2.5" test pipe, and then back to 3" for the rest....what issue would that cause?

 

[gsxeclipseguy]

yeah im not seeing what problems there would be

 

[KeltonDSMer]

If you plan on using your existing test pipe, I assume you are planning on making flanges for the other piping; or are you cutting off the flanges and welding? Either way, it would be easier to just buy a 3" test pipe and make it a full 3 inches through the whole system.

Now that I think about it, it would be pretty dumb to go from 3"-2.5"-3". It isn't "just a half inch" of difference; I learned back in 6th grade that the area of a 2.5" diameter circle is 4.9 inches squared and a 3" is 7.1. This means that a 3" pipe is actually a 45% bigger area than a 2.5". That is a lot of restriction.

Suck it up and go for the full 3" system.

Good luck with the DIY exhaust! I think it is kind of stupid to spend $1000 on some steel piping too!

 

[jl98]

get the 3" test pipe. It cant be more than $15 and you'll be sorry if you don't.

 

[DevilSperm]

sounds good, im probably gonna get the flanges from rre...since i wont go with the 2.5" test pipe ill probably just get a flex section and muffler clamp it on so it'll be 3" all the way back. Thanks guys