In article "Sukhi" writes: $I have a 1.8 T 2001 Golf GTI 150BHP and would like to know what the main $differences are $between this and the 180BHP 1.8Turbo found in the Audi TTs.? ie is it $possible to mod my 150bhp $to 180bhp and cost involved ?
You probably can't make it identical to a 180 hp version without replacing engine parts; I'm not sure about the 150 hp version, but the 170, 180, and 225 hp versions all have different compression ratios, which means a physical difference in the size or shape of the combustion chamber. Bore and stroke are identical, so it would be the cylinder head, the piston crown, or something about the motion of the piston; I don't know which it would be. (Compression ratio does not account for all of the difference in output; they don't all use the same turbocharger.)
As a previous response has suggested, chipping your engine would probably be the best way to achieve an output of approximately 180 hp.