Which company you would use for a remap would really depend on who you ask - most companies have pretty happy customers.
If you live down south, you have a few choices. Wherever you live, Revo will be an option as they have dealers all over, but they are quite expensive. Down south you have likes of AmD and Jabba, both have good reputations. Up north you could try Star Performance in Scotland. That would by my choice (I live in Newcastle though).
You should get about 210-220 bhp out of a remap assuming no other mods. If you have more mods, you'll get a bit more out of it. Then there is always the big turbo conversions (KO3, IHI etc) but we're talking big bucks there.
My engine yellow light was coming on in my Octavia 4x4. It was a coil on the way out that was causing it.
Thanks very much for the tip about the coil as my yellow warning light keeps coming on as well.. Apart from that, a really great car. Mine is the 1.8 turbo, but in L-K trim.. can't believe the kit you get for your money.. Superb car, would I have another one? You bet.
I have owned an Octavia vRS from new - bought in Sept.2001. I am not too happy with the reliability. Three spark plug coils have failed on two separate occasions whilst under warranty resulting in transport to a Skoda Dealer for replacement. Since the warranty has expired a Turbo Boost Valve and Temperature Sensor have failed (cost £360 to rectify) and now I have problems with the clutch - I suspect the thrust bearing is failing. All this and the car has done under 45,000 miles.
To the comments on the autocar review.
I have that copy of Autocar somewhere. I think they suggested it had the more powerful 225 Audi TT engine in it, because the acceleration and the weight meant that the power to weight ratio matched what it would have had with the Audi TT 225 engine in. Although obviously Vag/skoda refused to comment, and just denied that, stating it was standard!
It's the usual thing of car manufacturers giving car mags a more powerful version of their standard car to get better stats, so they sell more; a bit deceptive really.