wfocrx

I was just wondering because I plan on building the block over the summer and want to know if I'am going to need to upgrade? I know it would be better to run 3" dp+exhaust.

quicksilver1689

rule of thumb for turbos, less backpressure the better.

kenbdSi

What size turbo? I would do the 3 in DP. It give room if you decide to upgrade your turbo later in the future.

quicksilver1689

i would reccomend a 3" dp in pretty much any build over 275-300whp, free up some lost potential.

boosted92

Yep, you'll be able to make 400 WHP on a 2.5" exhaust, but that's not to say that you won't see some gains from a bigger exhaust

quicksilver1689

at 400whp~ a 2.5" downpipe is a bottle neck

DaveF

FWIW my old street car made ~450 hp/315 tq with a 3inch dp and 2.5inch exhuast. (81mm bottom end, stock gsr cams, t3/67 @ 18psi)

<FONT COLOR="red">click here to check it out</FONT>

blinx9900

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by boosted92 &raquo;</TD></TR><TR><TD CLASS="quote">Yep, you'll be able to make 400 WHP on a 2.5" exhaust, but that's not to say that you won't see some gains from a bigger exhaust</TD></TR></TABLE>

best answer right there /thread.

94_T3G

x2 on what boosted92 said.