Hi
Yes, you can get a map and be done quite happily.
With Revo results for stage 1 are around 270bhp. No other hardware required. Stage 2 requires some hardware but opinion on necessity and what exactly varies greatly. Your budget will also have some bearing on approach.
Other tuners will claim (and achieve in some cases) bigger numbers. Tuning these is not all about the numbers though. Remember it's a front wheel drive after all and too much torque particularly can be it's own undoing.
Have a read here:
http://www.mk5golfgti.co.uk/forum/index.php/topic,99608.msg982641.html#msg982641For info you don't need an intake for stage 1, although you may like one.
For me, and this is entirely personal, I would put the intake money towards a high pressure fuel pump (Loba). The OE fuel pumps can in some cases fail to deliver adequately throughout the full rev range. Not all have issues, but some can. Luck of the draw on manufacturing tolerances. A HPFP will ensure a constant air fuel ratio that your tune will appreciate and this will help protect your engine. After this I would go with an uprated intercooler. An S3 part is fine for up to stage 2.
After this sort the brakes. S3 kit front and rear is a substantial upgrade if you aren't going on track with it.
There are so many different ways to go about this and I'm not about to say what is right or wrong. You'll enjoy making your choices though!
If you want to drop serious cash on your car and it's a keeper I can thoroughly recommend an LSD. Wavetrac particularly. They work differently to the likes of Quaife etc. There aren't too many around with these so you may even get a little back at sale time but don't expect anything major. These really unlock the cars potential. Going to cost in the order of £1400 fitted mind you.
Bilstein B12 suspension kit is a great upgrade, Eibach ARB's front and rear aren't waste of money either, not forgetting an anti-lift kit (W.A.L.K)! In fact, do this early on. The bush it replaces is overly compliant and it will help prevent your suspension geometry changing under acceleration and braking.
I think you can see how this is going to go for you!
Enjoy!