The pulley and colder spark plugs are a must for power. i'd advice a 15% reduced pulley and a 1% oversize lightened crank.
On the S induction kit does give something, but not a lot. The best are GTT, Alta and
JCW (I like the
JCW including GTT insert as it looks really OEm and smart in the engine bay.
Exhaust wise I'd avoid the
JCW, expensive, not the best for power and defo not the best for tone/nice roar. The GTT reroute pipe or the Milltek are probably the best for power, noise and price.
Also I'd advice an intercooler upgrage (not the Forge one!) ... my stock IC really struggled with a 15% pulley to cool the inlet air enough in warmer weather and after being ragged it even struggled in cool air! Its expensive but I also found that the M7 ultimate hood scoop seemed to work strangly well at keeping inlet temps lower....its not pretty but does make the car stand out and biuzarrly seeams to work even on the stock IC