im wanting to build up my existing eng any suggests

 

define build up... are you talking about just throwin on some bolt-ons or like internal build?

 

Also, what engine are you building, SOHC or DOHC?

 

im talkin about a internal build up

 

dohc

 

Staying naturally aspirated? Staying with the 2.0L block?

You can get forged pistons and rods, preferably put into a freshly bored 0.020" over block. With 10.5:1 compression and possibly a timing retard unit, you can still run pump gas. There's really no more that needs to be done to the bottom end. You can get a lighter crank, but the gains are seriously not worth the money. Of course, having a good shop balance the entire assembly is going to help. I'd also recommend a crank scraper. If you're going to be at higher RPM's for long periods of time, a larger capacity oilpan would be nice, not really necessary for most folks though.

For the top end - really big cams, upgraded valvesprings, adjustable cam gears (and the madatory tuning time), and gasket matched ports will make a huge difference.

That's really it for the engine... Cleaning up the inside of the intake manifold and gasket matching will make a big difference. A good header (longer is better) is a must. An aftermarket 2.5" cat (stock is 2.25" outlet), 2.5" piping, and a good straight-through exhaust certainly won't hurt, and aren't very expensive. A larger TB (55mm is all you'll ever need n/a) and true CAI finish up breathing mods. An aftermarket computer and an UDP are really the only bolt-on's left at that point.

Best of luck!