Cobb access port plugs in to your car and allows you to flash maps to your car. There are standard stage 1 maps already loaded. You can do data logs, email them to your tuner and they can send a bespoke map for you whenever you make changes to your car. You can also flash the latest maps for the gearbox (TCM). Really easy to use etc.
As nurburgringgtr said...speak to an expert and see what they say. I've used Andy at ACspeedtech for all my stuff. Nice guy...knows what he's talking about.
ACspeedtech is in Warrington. I'm not sure the exact figures with Cobb stage 1 but I can tell you it made a really nice difference and took about 10 mins to do and I didn't have to take my car to a tuner to do it. Looking for £500 as new in box used 4 times in total.
Seriously...it's very simple and and I can guide you through it no probs. I'm out of the country for a couple of weeks from Thursday. This site has got loads of info on upgrades and helpful people. PM me if you decide to go down that road.
Welcome on board - if you are new it is worth chatting to one of the tuners directly and getting advice - most on here use either Cobb or ECUTek - both tuning/programming devices which can be used to map the car and gearbox software.
Iain Litchfield is my choice but SVM in Birmingham, ACSpeedtech, Sly @ Kaizer all have excellent and long term customer service and tuning reputations within the GTR community.
Regarding Auto Torque, I have used them for a couple of years with my Evos and can say from first hand experience that they Chris and the lads are very friendly and always willing to go the extra mile to help. Chris has a very good and professional set-up there and I would thoroughly recommend them to anyone.
It's a shame what happened to John but I believe that this is very much the exception rather than the norm (though I know that will not be any consolation to John).