I'd say.. somewhere between lightly and highly modified.. 'Medium modified.' His setup is (was) stock bottom end, pure 850, port/reflex, EOS manifold, axles, and Pure transmission. Fuel at the time was E98, unclear as to exactly what happened other than a rod went to the moon on a log pull. Blew...
It's more the other way around. You tune the JB4 for the additional octane. @Jesse DaBears Will walk you through it. If you're going Meth + JB4, buy the kit from Jesse, it hooks right into the JB4.