As some might no just purcshed a 1.9tdi im thinking of getting a nice stainless steel backbox for it now the question is when you put a backbox on a diesel would it sound the same as if you would put it on a petrol.

No, it makes practically no more noise than std.

oh doesnt it might aswell leave it then

The only thing that will give you noticable performance gain will be a remap / chip.

Tend to cost around £200, but will give 30-40bhp more and more torque - you generally get better mpg on cruise also

were would i get that done

Have a look round ebay matey

I found this one on my first search.

I got my 330d remapped and the guy came to my house and did it on the drive

nice find probably look more in to this after christmas thanks for the info though mate.

A mate may have a Tdi tuning box for sale.
I will ask what engine its for.