...BTW your Bieber avatar is awesome.-Malone
i think tdi with proper porting, manifolds, and turbos can make high rpm hp. much like a 1.6td you can't compare stock performance with tiny turbo, tiny valves, and crappy stock cast ports to a modified engine. higher rpm power has definitely been done, look to scandinavia, and thats the best way to make power, just like there is no replacement for displacement there is no replacement for higher revs, ur moving way more air so you're going to make more power to a point.
I think to have the TDI torque down low you will need a trans with a gear so tall it would be impossible. If you are worried about the 1.5 being able to pull at the high rpm then I would be worried about the TDI more. My TDI actually pulls better at 2,000 rpm than at 4,500 rpm. So you would need a trans that is almost 2x as tall to get it where it pulls best...these are generic figures to illustrate as you would not need a trans quite that tall but I think you will want the idi diesel rev range is the point. if you have a aaz and it hits peak torque at 4,000 rpm or so it would be more suited for what you want. Also why I think the possible idea of the 9a 2.0 is a great idea if it works