How tuneable are these engines? I would love TBs but just can't afford it at the mo. What other options are there? How much would I have to spend to get the power up to 140-150bhp? Is it worth spending the extra or just fitting a c20xe? I just fancy the 1600 because its lighter, newer, and it would mean I would not need to uprate engine mounts, driveshafts etc. This is for a Corsa BTW! Any help would be much appreciated!