What kinda hp gain?

[vntned]

Alright, my CSX currently is running about 17psi on a pretty much stock engine(forged internals and a FM cam) and has a stock 2.25'' swingvalve and 2.25'' downpipe with a 2.5'' catless exhaust and a bullet muffler. How much of a power gain will I get by swapping to a 2.5'' swingvalve with a 3'' downpipe and 3'' exhaust w/ a 3'' bullet muffler'. I already have that exhaust system laying in my shop and Im trying to figure out how much of a gain it would be.

[scott_s]

Circle Area = p • r² = ¼ • p • d²
Area for the 2.25 exhaust is 3.976 and for 3" is 7.068 = 78% more flow going to the 3" system over the 2.25".

If you are running a MBC you will see you boost go up probably 3psi (guessing) with the reduced restriction. Mine went up 5-6psi going from stock to 3". I would guess between 20-30whp. If the cost is good, and you do not mind a bit louder possibly, then it is a no brainer if you want more power and engine efficiency.

[vntned]

The cost is free! Ive got the whole exhaust system already, its collecting dust in my shop. Noise doesnt bother me at all. Im hoping this will be enough power to run with the LS1 Z28 my buddy just bought. As is its already faster than mustang GTs and the LT1 Z28s. I think 30 more hp should be enough!

[Juggy]

Ned, I just went from a stock 2.25" SV and 2.5" DP, to a TU 3" SV DP combo......also dropped the 3" kitty too for a straight pipe.....already had a 3" catback installed.....im guessin the car gained about 40-50fpt and 20whp?

its a 2.2L TII spirit 5spd, and it has enuff torque now to light the tires up 2nd gear from a roll!!! im only pulling about 15 psi tho, my grainger is maxed out so i cant get anymore, i think there is something up with the wastegate? I was able to get almost 20psi b4 the swap.