I purchased a 99 gtp with the following mods 3.1'' pulley 1.9 rockers ported blower ported intake manifold ported exhaust manifold 3'' down pipe u-bend and cat delete fenderwell intake trans shift kit and trans cooler tuned on hp tuners for 93 octane with kr. A fellow gtp buddy of mine said theres no way you can run a 3.1'' pulley without an intercooler due to spark knock. When i asked the guy i purchased the car from about kr he said the intercooler was not needed because all of the porting was more egi friendly and more part friendly the pulley is capable of 15psi boost but spiking 12 running 10 max the car pulls amazingly well theres no backfires or lag and the car revs down to idle smooth around 750 i plan on running it wot with a tech 2 and monitoring kr any suggestions to identify tune?

I would think you'd want headers on there to run the 3.1 setup. If it can't flow then you're just asking for it.

Don't know on the tune part.

Way too small of a pulley. The only way you could reasonably run that size pulley is at least with headers/cam, even then you'd be pushing it big time. Anything under 3.2" should have headers and an intercooler, if not a cam too.