I have a 1987 firebird lg4. COMPLETELY STOCK

I recently brought the edelbrock performer and manifold kit known as the chevrolet 264-400 (egr) {you can see the combo in summit and jegs}

is this a good combo(I should have asked before I brought it)?
give me a good hp estimation please.

also, I plan to replace the whole exhaughst system, maybee some L69 ported heads.

give me some hp estimates, opinions etc...

P.S. i already did a search but im not satisfied with the info

THANK YOU FOR YOUR TIME.

 

The intake may get you 5-8 HP and tq. I've always noticed on a relatively mild or stock engine that when switching to a dualplane intake, the off idle response is a bit better and it will pull better up top.

Don't expect a tire shredding bolt on though.