I'm having my motor built it is a low compression b16 motor 9:1 compression..I have a t3 60 trim w/63ar and will run about 15psi..

I'm useing my old gen1 head it has over 120k on it so i'm gonna replace the valvetrain..I'm useing GSR cams..

My builder recommened me get 1mm oversized valves then thier gonna do a valvejob opening it up for the oversized valves they said it would flow so much better..I've talked to alot of people and done some searching and now i'm getting scaried about going 1mm over..I'm sure my builder knows what thier doing they have a great reputation with winning cars but i want a reliable build that makes 300+hp and can be daily driven..

 

stock valves should be fine for that power level

 

stock or .5 is good