I don't have an LS1 but I do have a GMC Sierra 4.8L with a Powerdyne Supercharger. I get some audible knock at ~5000 RPM. I am using the FMU that came with the kit, and the Predator programmer that recalibrates the ECM for the blower. I have taken out timing and added fuel, as much as the predator allows the user to. I have not changed my plugs and I think that will help me.

I see everyone recommends NGK TR6's in both the LT1 and LS1 sections but the plug design is different for these engines. The 4.8 has a long threaded area and an extended tip. I tried using R42TS's like a parts store guy recommended, but they were wayyyy wrong.

My question is what plugs (part number would be nice) should I use and what gap should I start with? The factory gap is .060.

Thanks!!!!