just wondering what is the biggest single turbo anyone has used that would still have some street manners. no towing.

 

Industrial Injection has the silver bullet 66/14 and new phat shaft 71 (k31) or HTT 66/16 (stainless housing).
I'm sure there are other guys running bigger turbos for pulling and stuff but these are the ones I think are most popular.

 

Maybe the A5000, thats a big single. I hear they now have the 6000 series?

 

a5k here and I would find it hard to believe that anybody runs much bigger for a daily ride but who knows.