There is a lot of mods you can do to your Vantage to increase the power and imporve the already great driving experience. To name a few, ECU re-map, TCU re-map, sports cats, sports exhaust, upgraded brakes, brake cooling kits, air filters, suspension, aerodynamic enhancements. We have done all the above and more to our 4.3 demo car with some great results.
To answer the above post about the sound increase when adding sports cats and keeping the OE exhaust, yes it will be a bit louder but in no way OTT our sports cats are 200cell making them alot more free flowing than the OE 600 cell cats making them an ideal addition to the Aston power package.