Just try a cold plug for now. Then you can start tolean it out as you ar esupposed too. When you use a hot plug, you advance the timing alot and this will actually give your engie less topend power. Your torq could be good from low end, but as soon as you hit some rpms, it will loose power and run hot. espesially since you already have removed a shim. if you are to test with 40%, make shure you add some shims and use a cold plug.