Realistic gains going from stock (2.5") to 3" catback?

[turbosam6]

Right now I have the stock exhaust with high flow cats, Moroso spiral Flow mufflers, and rear muffler deleted. It sounds OK, but needs to be a little louder. My side sill are still getting hotter than I'd like, so I'm gonna ditch the cats soon. So it will be 2.5" with just the moroso mufflers. Will getting a 3" cat back (like the Borla or whatever) really gain me anything power-wise? My car is stock except for smooth tubes, K&N's, and the above mentioned exhaust mods. I do plan to either spray it or (hopefully) install a Roe s/c, but thats in the future. I don't wanna drop a grand into a catback for a gain of 5 HP.

[bushido]

High flow cats vs no cats is like a 5 to 6 hp difference. Not worth it IMO. If I were you. I would just scrap that exhaust of yours and spend a grand and buy a Borla system..

[GTSNRT10]

You will lose power going 3" vs. 2.5" prior to blower install

[RTTTTed]

Since you've already got high flow cats and lost a muffler there wouldn't be much hp gain going to 3" after the cat. Maybe 3hp? Most of the restriction is the cats.

With a GTS you will gain something by enlarging the pipe turns, just not much. With a Roe or Nitrous you'd see significant gains.

Ted

[Joelcool]

Keep the cats....the smell isn't worth the 5 hp IMO.

[turbosam6]

Originally Posted by Joelcool

Keep the cats....the smell isn't worth the 5 hp IMO.

I know, but the heat worries me.

[EDELECTRA]

Originally Posted by turbosam6

I know, but the heat worries me.

It should lose them less int heat and easier on you wife or girlfriend calfs

[b3rndtt0ast]

Originally Posted by Joelcool

Keep the cats....the smell isn't worth the 5 hp IMO.

it smells good. i love the smell of unburnt fuel. leaded gas is even better.