i have been looking around when i get the chance but dont see a whole lot of options as far as replacing the wastegate on the stock s4 turbo. i would like to upgrade turbos and everything but dont have the money quite yet to do everything i'd like. what would ya'll recommend for the s4 turbo wastegate?

 

Only 2 options you have is to port the stock wastegate or buy a used S5 turbo.

 

http://www.aaroncake.net/rx-7/s4wastegate.htm

 

Well you can't replace an integral wastegate because it's... integral. But you can easily improve it's performance by making it bigger.

https://www.rx7club.com/2nd-generation-specific-1986-1992-17/serious-s4-wastegate-porting%85-343788/ (scroll down to post #15 for reposted pics)