what's next after intake, header, & exhaust modifications??

 

Car? Engine size?

 

if its a d series u should just boost

 

The camshafts are the next logical choice for upgrade. The reason is ease of installation and price as well as function. A good cam (or cam in the case of the D15-16) can increase your power more than any other single bolt-on and can complement your IHE upgrade hope this helps. Bisi has some really good cams for the D-Series engines.

 

You can't just get a cam and expect the rest of the valvetrain to last very long unless its a mild cam. Rebuilding the head and getting arp head studs and a new head gasket would be the next step. The head can come off without taking the motor out so thats a plus. You will also need slightly larger injectors and a tune if you want to get the most out of your setup. Its an on going never ending process, you will never be finished.

 

That's why I was asking about which motor. Because you might as well save up for a swap if you have a dseries for the best bang for your buck and at least you could still retain your exhaust and possibly your intake and sell the header to pay towards the swap.