Sjdickso said:
A box is the cheapist option, if you are to go for map i would not have a cheap one from a mobile unit it could cause more issues in the long run, i have heard to many bad stories from cheap maps.
If you can afford to spend out a bit more i would get one of these boxs.
http://www.diesel-performance.co.uk/
That is the box I have on mine. If you sign up to AstraOwnersNetwork, and pay £10 for a subscription, you get £80 discount on the DTUK box.
I've got the eco3 on my SRI150, and it's bloody fantastic. I had one of the german E-Bay boxes, and found it to be VERY aggressive in the power delivery, but the eco3 is adjustable, so worth the extra money.
Should be good for 160bhp+ with one of those boxes, and 100% reversable in 10-15 minutes