IMHO either pay and trust a good tuner (as you've already done with the JWT ECU) as they're using the right equipment and baking in a little margin for safekeeping, or refine the OEM system yourself with the aid of Sam's KnockSpy software. I think J&S is overkill unless you're planning on changing things a lot requiring constant attention -- like if you're a racer trying to eek out every last pony every day.