As title, Reason I ask is I want to get a Milltek Catback. Having checked 2 cars last weekend who both have Milltek cat backs, one is louder than the other? Even on idle. Only difference is that the louder one has a stage 1 remap.
Looking at an exhaust that isnt drony but purrrs a little better than stock and has nice DSG farts (LOL)
I can't see a remap making a car louder on idle. Maybe the louder car had a precat delete on the standard downpipe? Under load, possibly. Also, it's not an exact science, two cars with the same map and same exhaust might sound a bit different. Most exhausts 'bed in' a bit over time and sound slightly different 6 months after they're fitted.
I'd just try and find a resonated cat back. The non res version is probably going to be louder than you'd like. Give Nige a ring at Powervalve, see if he'll do you a bit of forum discount
Or... stop fannying around with cat backs and get a turbo back
Even keeping the stock cat back and fitting a proper 3" downpipe with a sport cat would be a better idea I reckon, you'll be able to get a Stage 2 map and also get a nicer sound, with louder burps.