My brother is building a naturally aspirated setup on his car.

It's a D16Z6 with PG6B (dommed pistons), ported head, 2" exhaust.

We want to know how much can we rev the engine on stock valvetrain and if can we use some aftermarket cam??

Thanks.

the major thinkg that will change how high u can rev teh engine is the head. first u need cams that can make power at a higher rpm, new cam means new valve springs too and probably valves. best way to tell is a dyno to see where ur engine stops making power