Need some input...

I'm planning to add fenton headers and duel exhaust using 2 1/4" pipes on my '60 Chevy with a stock 235.

Also I'm either adding an adapter on the intake manifold to bolt on a 2 barrel Carter carb -or- I'm going to change the intake manifold altogether in order to add the new carb.

My question is, how much more HP and torque may I expect with this setup? I'm not looking for a lot but 15 to 20 would be nice.

Thanks.

1960 Chevy Apache 1/2-ton
1965 Chevy Half-Ton Suburban
1966 Chevy C60 2-Ton

Stupid is as stupid does. - Forrest Gump