so I'm building my C5 and I'm changing out the pistons with CTR and I figure that should raise my compression to around 12.2:1, What I've been told is that a you can't use pump gas engine anything higher then 11.5:1 compression. the mods I plan on doing is a JUN3 head package and the CTR piston's, So is it true that you can't run anything higher then 11.5:1 and I'll have to use race gas?, any info is appreciated thanx in advance

 

Personally I wouldn't go above 11:1 compression for daily driver car on pump gas unless your comfortable tuning your vehicle or have a reliable shop to do it for you.
As far as compression, that is just recommended, but I have friends with street civic's running 12:1 and almost 13:1 compression, but let's not take for granted that these are highly skilled tuner's and know what they are doing. So really it is what you know, or who you know, that will determine how high compression you can run safely on the street. I wouldn't suggest higher than 12:1 if daily driven and properly tuned

 

I'm actaully either going to have a local guy that I know personally that does really good tuning here or drive down to cali and have import builders install and tune everything