The forge twitercooler has been PROVEN to work, so you know you are getting a product that does what it says on the tin.
You dont need the intercooler for stage 2+ anyway, its a nice to have. There have been quite alot of us who have ran at stage 2+ whilst retaining the stock intercooler. Mine was around 8hp less than an equivalent stage 2+ car fitted with the intercooler.
All that is needed for stage 2+ is the downpipe with sports cat and the HPFP. Mods such as the intake, intercooler etc are just icing on the cake.
What stage and tune are you running now?