from what i gather the main reason you shouldn't run a stage 2 map on a car with a standard downpipe is that the engine gas temps will get to high.
So......
If i was to knock out the pre-cat right next to he turbo, im thinking the stage 2 map wil be fine, as there wont be that huge restriction as the red hot air leaves the turbo, and if i stick on the HPFP ill be able to go back to stage 2+ again. obviously it isn't going to flow as well as an aftermarket one will, but its surely going to be one hell of a lot better than standard.
the reason i ask this, is that since strippin all the mods off my car, i still have all the remaps i have had from sharkperformance on my handset so i can go straight back to stage 2 and 2+ easily