I don't have an answer to your question, but I have the same sort of problem below about 3000 rpm and was hoping Gary's fix would do it. My trouble is that my mechanic skills aren't the greatest and I don't want to get this thing taken apart any more than I'm sure I can put back together correctly. Did you have to remove the intake manifold to install Gary's fix? Did you actually remove the knock sensor from the block as per Gary's instructions, or did you leave the knock sensor in and just splice into the wire? Is there a trick to this? I'm having trouble getting at the wire and connector. The Haynes book says that in order to get to the knock sensor you have to drain the coolant, remove alternator & a/c compressor, remove intake manifold, etc., etc. Since Gary's page says "installs in minutes" I would think there's got to be a better way, but I can't figure out how. Kruf or anybody else who's done Gary's mod, I would appreciate any hints or tips.
1997 Legacy GT Sedan
1995 Suzuki Katana 600