I was wondering if I will lose horse power or whp by adding a 3 inch catless downpipe. I have an 06 SS/SC with gmpp stage 2 kit, GMPP header, GMPP sport cat back exhaust, Injen cai and ingalls torque dampner.

 

You might lose some power down low, but gain it up high...

 

i wouldnt use a 3" with a 2.25" catback...

i would go with a 2.5

 

So i would be better with the stock dowpipe and would I see better times at the track??

 

Not so much the stock dp..

there are 2.5 replacements that flow a little better..

matched with headers theyll be that much more noticeable in gains.

 

ok thanks.

 

yeah 3" to 2.25 kinda defeats all goals

 

agreed go with a 2.5 you will enjoy it more

 

That is what I was thinking. That will probably hurt my dyno numbers with my current mods right???

 

ideal for a 2.0 sc lightly modded would be a full 2.5 header back imo

youll get a wierd curve

 

any ideas on who makes a good 2.5 downpipe?? and shoud I go catless???

 

Only go catless if you dont have emissions to worry about...

Cobalt Addiction makes a nice header that bolts to stock exhaust manifold.

http://cobalt-addiction.com/products/pages/headers.html

 

Ok I will have to check it out. On the dyno will I do better with the 3inc or the 2.5 inch? How much do you think the diff will be in numbers?

 

2.5" will be better with the catback you have now. also the size has alot to do with the power your going to make..

I use a 3" dp with a 2.5" catback, because im not making enough power yet for a full 3". And i chose to let my headers breath, since they have a 3" collector..

Im not sure if the numbers will be much, but the difference will be noticable..

Someone once gained like 10 hp on the dyno from going down to a 2.5" catback from a 3", because they werent making enough power for the larger diameter.

 

Ok I have a GMPP 2.5 cat back, GMPP header, Injen cai, GMPP stage 2, and ingalls torque dampner? 3 inch or 2.5 inch down pipe. With the 3 inch I dynoed at 235 whp and 220 torque. So shoud I save my 3 inch for later and go with a 2.5 inch for now so I can see more numbers on dyno?

 

why would 3" dp and 2.25 cb defeat all goals?
it actually may help flow to have a larger diameter up front and slightly smaller in the back due to the way exhaust gasses lose velocity as they travel. exhaust gas scavenging effect.

You wont lose any power unless you have 3" header-back without enough mods push a large amount of air.

 

So I should be ok then and I will have more power with the setup i have now???

 

Slightly smaller.. yes.. but i think a 2.25 exhaust is is a little too much...

 

2.25"... blame GM for that one. probly will go 2.5" axel back eventually and keep my 3" dp.

 

I like the sound of my 3in catless downpipe. Just wanted to know about the power i would gain or loose by having it on?

 

weve answered this a couple times...

you will gain power by going to 2.5 with a 2.25 catback

if you get a bigger cat back, get a bigger dp.

 

thanks for your help

 

no prob.