It won't be too loud especially if you have the resonated cat-back so don't worry. If you'd rather have a sports-cat though then hold out for one or buy a 3" downpipe & sports-cat now. You can then save up £300 for a decent FMIC at another point and go for stage 2. Alternately go for stiffer suspension & ARBs or ARBs, engine mounts and polybushes to get the traction down better.
Believe it or not £600 is a fair amount to spend on mods for this car so you can potentially get some major parts sorted now .
Consider an LCR brake uprade perhaps or 312mm upgrade? It's totally up to you which way you go.
think your spot on, there is so much i could do with the money that i just cant decide. brake upgrade is a good shout, but sstems back to wanting bigger wheels and suspension. Now the sale section is closed, bargains are hard to find It may be a better option to go FMIC now, then do downpipe and stage 2 later. This would stop us having issues with EML at a guess. Only had stage 1 a week anyway..........