Ive been doing some googling and have found various information. Some says use a 44mm for anything at 600 hp or over and some says a 38mm will be fine for 600. since my goal is somewhere between 600-700 what size should i get? also some advise on spring size would be nice.

 

what turbo and whats your set up? at that power goal might as well used the 44mm wastegate .

 

HP isn't the determining factor, since your not making HP with the WG. Pressure is, specifically intake pressure and the exhaust manifold's backpressure. With a giant turbine and low boost, you need a very large WG. Many racers use multi-stage boost control (electronic, based on gear), and need to run low PSI to get traction in 1st. Street cars running over 400whp generally HAVE to do this to get any help from the low gears gear.

Its been common for a while to use dual v-band 44's because its the most simple way to get a fully divided setup, and not have to worry about gaskets. If you plan to only use it on the track and its undivided, I'd get a 44mm or a bit bigger. Dual 38mm v-bands will be fairly common for divided manifolds in the coming years, IMO.

If price is a concern, you really shouldn't be running 700hp. The price of a wg is nothing compaired to what you spend on the overall setup.

 

Im running a gt35 with .82 ar housing. I have a ramhorn with a single 44mm gate doesnt creep even half a pound of boost. Making 510/350 on 19psi pump

 

a little more info on your setup would deff help us out here, tial is 1000% the way to go as far as a manufacturer goes so give some more insight into your setup and we can tell you which size unit will fit your needs.

 

making 600-700whp the 44mm would never hurt

 

What are the specs on the block? If u dont mind sharing