just bought a clio williams 2. its got a decat scorpian exhaust on it, it is very loud, i was thinkin of swappin it for an omp grp n decat system, as i think this will give me better power as it is developed for making power on rally cars. any1 got one or know if there any good. also my induction kit is a huge powerflow one which makes a s**t load of noise and i think it is restricting my power. should i put my airbox back on with a uprated panel filter. also looking for a 421 manifold, which one should i get. also i have 17in prima racing williams replica wheels, will these slow it down a bit, should i put some original willy wheels on. cheers for any help.