(dadofthree @ Dec. 24 2006,20:29) Did I detect some popping? Any backfire ? I've always heard about needing back pressure or you would hurt the engine, but several guys on this site have stated many, many thousands of miles without trouble. A dyno would be good to see the effects. A combustion engine is like a compressor; if you eliminate restrictions in the exhaust it should run better, however without eliminating restrictions in the intake in combination should lessen the effect. I'm no motorman, so maybe one will read this thread and straighten me out. I've also read and heard that slipons don't help much and that most of the restriction in the Busa comes from the exhaust manifold or header, so removing the cans wouldn't seem to make a big difference except in the sound levels.