What sort of numbers are you looking for Martin? Gumball is running circa 440bhp with the Andy F ECUTEK remap. Remember that the first map includes the licence, any mapping after that you're just paying for a tweak to the map.
Gems will give you extras like anti-lag but do you see yourself using that?
I'd personally love anti-lag, not for the performance, but just for sitting at the traffic lights scaring the hell out of everyone as the cars going off like a shotgun. But I have to ask myself, is it really worth the extra?
MoTeC - The dogs danglies, but surely overkill in a massive way. Only Calder supply them in Scotland that I know of.