If you want to amplify the exhaust note for very little, you can buy some decat pipes, which you put back on for the MOT, you can also knock out the exhaust baffles in the main silencer with a hammer and steel rod . It won’t sound as good as a complete aftermarket system but better than a standard system. You could also remove the rear resonators and replace with a bit of polished stainless pipe. - effectively leaving you a straight through system as the main silencers area straight perforated tube .’