ECU Question

[The DJ 27]

I have a 1.4 SEAT Ibiza. Reading my owners manual, the engine comes in three versions. 60bhp, 75 bhp (which I have, I think), and 100bhp. Looking at the data in the manual,this is exactly the same engine, so the difference must be the ECU (correct me if I'm wrong). How hard would it be to change ECU's, to give me 100bhp, or is there more to it than that, like different pistons and such? And how much would it roughly cost?

[The DJ 27]

The compression ratios are very slightly differnt. 10.8:1 in mine and 10.5:1 in the 100bhp version. Would this be down to the ECU, or different valves and pistons?

[The DJ 27]

So, if i bought a head gasket off a 1.4 Sport (or whatever they're called), and fitted it to my car, the ECU conversion would be fine?

[The DJ 27]

Yeah thats true, but, VAG are notorious for offering the same engine with different outputs. For example, the 1.8T comes in 150bhp to 225bhp forms. Different cams wouldn't be a huge problem, as I'm planning to uprate them anyway. Any ideas on which companies I should talk to about what I want to do?