Hi and welcome to the forum...
Don't bother with an induction kit, they are generally rubbish. OEM airbox and filter are good for 300bhp but you can change the filter for a Green filter will improve the throttle response a bit and you will be able to hear the DV dumping boost better.
Exhaust change will just give you more noise as the restrictions are downpipe and CATs. Changing to a 3" downpipe and sports CAT will give you earlier spool and better response.
Only other thing thats worth doing engine wise at your level of tune is a FMIC which will allow you to run a little more timing advance with your revo box.
Then of course brakes and suspension could do with a look in... Ferodo DS2500 pads for the front and there are plenty of threads here on suspension changes... Bilstien B8 dampers and H&R -25mm springs being about the best out there.
<tuffty/>