My son has just had a  custom made stainless steel full exhaust system fitted to his 1.0 Monte Carlo and Its transformed the cars pick up right through the rev range in all gears. The biggest improvement has been the near elimination of the significant flat spot around 1200 revs. Thankfully he opted for a resonated system with twin round tailpipes and as such it has a sporty but subtle note. The exhaust specialist he used has made such a neat job of the cut out to the diffuser that you cant tell its not factory. 

 

If anyone is considering having this done but is uncertain, I'd encourage you to take the plunge as I'm sure you wouldn't regret it

Who did he use?

He used Pipewerx who are based in Lathom near Ormskirk in Lancashire. They are highly regarded on the Biker scene, but also have a smaller operation making customised exhausts for cars. The car section is run by a guy who was number 2 to Ian Birch who used to own and run Dubsport ( very well know in the VW Tuning scene in the 1990s).

 

Ive used them before when I asked them to make Stainless "copy" of the exhaust system on my wife then Alfa 159 and both then and now the quality of the work is the best Ive seen

 

Hope this helps