I fitted my short shifter recently but when i accelerate above around 15mph it starts vibrating really fast and making a fairly loud noise i have fitted the rubber spacers/washers at the end of the shifter and i cant seem to work out what else it can be, all the bolts are as tight as i can get them.
Ill gladly try any advice thanks!

 

Its bumping against your exhaust. It was doing that to me too

 

Probably hitting your exhaust, mine does that at idol.

 

or you can change the rubber bushings that sit outside of the shifter

 

I changed the bushing by the shifter but couldnt fit the one at the end of the main rod.
What can i do to stop it rattling?

 

get a longer exhaust hanger for the center section

 

I had an aftermarket exhaust, and it had this hangar piece that was hitting, so i just choped that off, and its all better now.