recently bought a 85 iroc over here in australia, everything is stock except the exhaust has been worked a little bit.

Looking to do little mods to the engine that will add up the hp gain.

So far im planning:

headers
larger throttle body
high flow fuel pump
larger port injector
take out air pump
3" exhaust, maybe the Borla catback.

Can also take out the cat as its not legal over here to have one, but will this help?

How much hp do you think ill gain by installing the above list, and any suggestions and recommendations are very welcome.

 

TPI, I presume?

Of those, only the exhaust will help. Removing a stock cat will probably help, although high-flow replacements don't tend to hurt flow. Headers and good flowing exhaust is typically worth about 10%.

The throttle body and injectors won't help unless you do something else to improve the engine's ability to pump air. Porting the plenum often helps, though. Removing the A.I.R. pump will reduce weight by a couple of pounds, but otherwise it doesn't take significant power to run. The fuel pump won't help unless your current unit is weak.

After exhaust, you'd need to get deeper to see real improvements - cam, head porting, larger valves. After that you're looking at expenses such as shorter/fatter runners, porting the base, and so forth.