Performance/HP Gain

Ok i have an automatic Acura EL (D16Y8 SOHC 1.6 Vtec) and i'm having the head ported/polished, but what concerns me is the exhaust... I'm doing a Full system with a header highflow Cat and 2 1/2" Pipe and i was wondering if anyone would be able to give me an idea of what kind of difference i'm gonna get with this new Exhaust... HP numbers would be great to know but i just want to have an idea of what to expect...I don't want to throw this money away and then get the car and be like.... Screw this i am selling it, I want to notice the difference (i know the Super charger is the next step for HP gain).

If anyone could help me out here by giving me an idea of the improvements this exhaust will make on my car i would be very greatful!

Thanks,
Lunis