I installed my Invidia Q300 a week or two prior to installing this 3 inch K-Tuned catless downpipe, before the downpipe this didnt happen. I have what almost sounds like a whistle under acceleration. I just wanna be sure its normal for this car. I used all new hardware, Used copper gasket as instructed by K-Tuned to seal the header to the downpipe and downpipe to the exhaust. I also have a rattle I have to track down, think I may have bent the heat shield trying to get the stock downpipe out.