Im just getting ready to buy a s475 for my mild 461.I can give a description and if you have any recommendations I would appreciate it.
Mild 461 cubic inch bbc eagle crank,rods and ovalport heads.Im hoping for 700-800hp at crankshaft.Im buying a s475 from a vendor on this site and im going to use 2.5 crossoverpiping.My question is since its a split t6 flange do I use 2 wastgates or 1.And what would your recommondation be as far as size of either 1 wastegate or if 2 what size for 2...The split flange in the s475 has me alittle confused..thanks for any opinions...

 

i would use two in the 40's range (depending on which company you use)

 

I run 2 precision 46mm w/g on my 347 with a BW S476. 2 w/g will give you better boost control on a larger c.i size motor like yours and help try to control back pressure some at WOT.

 

That's called a tangential housing. You don't need 2 wastegates because of it. That's not to say you can't use (or don't need) two...