The new 2.0TFSI is a flywheel side chain driven engine.
I don't think it will sound different due to the change from belt to chain.
But a quat exhaust can gif it a different sound then the S3, beside that the question is will it be a valve exhaust or a non valve exhaust.
What ever Audi do is still will sound like a 4-pod, a exhaust can't change that.
The torque and turbo lag will not change for the better if Audi give it more power.
They can only change the torque and turbo lag for the better by making it a TSI Twincharger.
In that case they can even put on an bigger turbo to get 300+ hp out of it because the compressor will take care of the turbo lag by lower refs.
But like i sait before, i like the new TT very much but not the engine line-up include this new HP 2.0TFSI.
Also a VW 2.3 VR5 TFSI will no do it for me, it will not come close to a Audi inline five.
Therefore the chance that i ever buy a new TT is very small.

Hans.