Hey i was just wondering if 12.5:1 compression is ok with my stock gsr? i know that stock compression is 10:1 if im not mistaken and i would probably have to run 91 oct. to eh? would i notice th edifference or just get 9.8:1 or 9:1 compression pistons?

 

if you want to go boost drop the comp a little... all motor bump up the comp... if you do go 12.5:1 93 and up oct is what you need to run if im not mistaken... if i were you and i had the money i would go boost... lots faster with the right parts and tuning...

 

With 12.5:1 compression and only 91 octane you'd need a hell of a tune. Also you'd be undercammed with a stock top end. 9:1 or 9.8:1 pistons would cause you to lose power if you're not going the FI route.

 

^ agreed

 

so with 12.5:1 with the stock engine, would i notice the difference? If so how big about? like 5 horsepower if that?

 

max hp is not from what compression you are running, but how good the tune is.