3” exhaust is overkill for the 318, you won’t get the proper scavenging effect and actually might be losing power. Carb, intake, cam , exhaust, etc. must match to make a good formula. Bigger isn’t always better if disproportionate.
I don't know. I never have supported the "needs a little back pressure" theory. I think if he can afford the 3" system now, it'll be there when he upgrades later on. It's certainly not gonna make the difference between it having good power and not.
