Looking to port the throttle body on 2002 z28 (5.7l ls1 auto).Worth buying a 90mm tb and 90mm intake manifold(tsp) or stay stock with the intake and port the tb myself? Think I have a stock 75mm ls6 manifold. Same basic question about the heads. I have a friend who can do it for a reasonable price I'm sure, worth buying new heads. ($1600 through tsp)

 

would help if we knew what the setup was on the rest of the car.

porting the TB is not a bad idea on any engine. it won't make a huge difference but it can't hurt (if done right).

the big intake manifolds like FAST LSx are not worth the cost on a bolt on car. if you are running a big cam or a h/c setup you'll see benefits. but it's still alot of $$ to fork over for 15hp more over your ls6 intake.

and heads are the same way. if you are running a cam than the heads can free up alot of power. but on stock cam the gain is minimal.

and budget porting is just that...budget. you never really know what you will get. your buddy could easily screw up the heads enough to actually hurt performance.

more info is needed for a better answer