First of all why do you want to fit a dump valve to a TDi? Is it for the sound or for performance? If its performance then don't bother because it will have an adverse effect on your performance. If its for sound you can achieve a reasonable effect with an electronic dump valve but this will cost you up to ?300. Its not something that's really worthwile imo but depends on whether you have money to burn or not. Do a search and you'll find some information in this forum.
There is no debate, its about whether you want the noise or not.... ppl's opinions are bound to differ. It cant be a waste of money for those wanting the noise. You get practically nothing from a cat back or exposed Filter etc, but ppl will gladly pay ?200 + for them.
TBH i think that if the noise is fairly subtle ill defo be buying one, as its one way to reduce the 'dervness' of the car lol.
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