In my signature.....
Duron 800 @ 1050 with Global Win FOP-32 (140 x 7.5)
Abit KT7A-Raid Mobo
512 mb (Crucial Stuff CAS 2)
Hard Drive Cooler
Elsa Eraser X2 Gforce with Blue Orb (modified to display as a Quadro and overclocked http://www.tweakhardware.com/guide/quadro/ )
Sound Blaster Live Value
Full Tower with 5 (120 mm) case fans with seperate PSU
Well the improvement can easily be disputed because it does not show up as a greatly in benchmarks, however I personally believe that it does make a improvement in clarity especially in Q3 where although not obtaining a major improvement in frame rate, it does allow me to run more detail without displaying a frame rate loss compared to the standard card.. The only times you can obtain a undisputable improvement is when working with photoshop. Overall rather than lie and say its great, I think its benifits are more visual clarity or even perhaps in my own mind, however I would do this modification again if I had a standard Gforce.
Im sorry I cant make statements about massive increase's however I personally think its a improvement and that is all that matters, but I have to look at the modifictaion objectively and dont wish to lie to you
I did a lot of research on this since I have a card that would do well as a Quadro hack. The performance will be in image quality and not benchmarking (as the prior post pointed out already). You will need to look for your particular card, since the reference boards have slight variations between model/manufacturer's (hence the resistors that need to be moved will be in slightly different locations). I started my search with Yahoo and worked from there. Good luck and steady hands!