You have to retune it for higher octane gas or E-85 blends or you will see minimal to no gains at all. More octane needs more timing and sometimes a leaner mixture (not true with oxygenated fuels) to burn properly.

 

its "suggested" on the stock tc, cant say for the sc.

 

There is no reason to put 87 in when you get 93 only two bucks more a tank...Your pulling boost so you need higher octane or you get knock. I run 93 most of the time unless Im in an area that only has 91 octane when honestly I don't see the difference and there is no knock.