theres plenty of info on the US side of the site, theres a seperate forum for non-turbo'd cars. loads of info about upgrades - exhausts, de-cats, intakes, tunes etc.
i think the 'easy' upgrade is the change the intake/manifold and update the software, as long as you have the right version of the engine, which I think you do.
this mod then makes it a 330, rather than a detuned 330.
ive not see anyone do this on the UK site though