i will running a pfab elt manifold probably with a 6265 precsion turbo and a 600 hp precision intercooler, im ordering my piping this week, confused about 2,5" or 3" whats yours opinion on that

 

horsepower goal?

 

For anything under 700whp, 2.5" is fine. You'll run into clearance issues on the hot side with 3" piping on most setups.

 

480 500 maybe 600 if i buy a watermeth kit for drag race

 

ive never ran anything but 3", looking up to all the big hp guys with rediculous builds it only seems standard. it dont know if it would net x amount of hp at certain psi level but i would expect the turbo would like a more efficient flowing pipe at higher boost levels, not 100% sure

 

I'd agree with this, ,700whp is a decently round number.

 

ok my down pipe will be 3" for sure, but i was talking intercooler piping, i hesitate between 2,5" and 3"

 

one more word for thought, i would probably just go with whatever size inlet/outlet the intercooler has to match size, if you have 2.5" intercooler endtanks theres no real need to go to a 3" intake piping. if your endtanks are 3" then id go for the 3"

 

my intercooler is a precision 600 hp wich is 2,75 inch

 

I am using 2.5" intercooler piping and making 741 whp with no issues. 2.5" piping will go farther than most think. You have to remember, if you're still using the stock throttle body, even with 3" piping, you will be bottlenecking it down as soon as you get to the throttle body. So, 2.5" is just fine for big power and even so up to probably 800+ whp before you would notice any difference and I wouldnt worry about going any bigger until you have also replaced the throttle body with a larger ID unit.