Well I got my SOHC Vtec D16Y8 swap done in my 91 Civic. I am in the process of converting it to OBD1 with a chipped P28 and 450cc dsm's. The motor is runing 10.5:1 JE pistons, DC 4-2-1 header, header back 2.5" exhaust, and short ram intake. The car is kinda peppy as is. Have been told I can get a bit more power out of it with a good tune.

I will be going turbo after I learn how to tune well. So my question is how much of a power increase can I expect off a good NA tune?