Hello to everyone!!
Everytime I'm about to get going in my S, When it goes down in REV's the engine or the stock exhaust system starts rumbling and vibrating. It's normal or not??? Or do you guys/girls think I should take a care of it???

 

I think this thread may be of some use to you:

https://www.s2ki.com/forums/index.php?showtopic=275252

Craig

 

I have the same problem- when u accelarate than de-accelarate round about 4000rpm i hear this noise. sounds like the exhaust-but i can also feel it on the shifter.