what do they use?
if they say stainless steel, find out what grade stainless steel.
you might find its not quite the fit and forget you think it is, but then again it might be, but its worth checking when its costing best part of £300.
The v6 sounds gorgeous when good fruity pipes are used, just look at a few on you tube, but incidentally, you can go very fruity at the back end but only if planned and built properly, it should not boom inside the car at all, or rattle in the valance either!
mine is decatted, and then piped up to a single rear silencer, twin exit, and sounds fab, and has no booming inside at all, at any speed, just a gorgeous V6 song on the throttle, quiet on the cruise speeds and flat throttle.
careful on the choice of rear silencer too, there is little room to get a decent size box in between the valance and rear axle, so many folk fit too small just to get it in easily, or use too large and end up with awful pipework tryin to get onto the entrance of the box, and your tips are 6" beyond the valance like rear cannons!!
good luck, i'm sure it will be pukka, but make sure they will consider the above properly, and do check what material they are using.