General Exhaust Problem

[Adem1]

I have got a performace backbox fitted on my fiat punto mk2 mia, i bought it like this and since i have had it i go over speed ramps and it keeps knocing also there is a lot of rattling going on, can anyone help me on this??

 

[5abr3]

I would start by checking the mounts on it to ensure they haven't been shaken loose or damaged.

 

[richie.guy]

It won't have been fitted properly, there won't be enough clearance on the rear beam.

It needs adjusted.