260/270 is pushing it on a std K04-15 TBH. More like 240-250 with a decent tuner.
I made 250 on my Outlaw turbo in my B5 but with a "generic/custom tune" and all with std injectors. They were running at 100% duty on WOT.
I am now going outlaw with 340cc injectors, FMIC, Sports cat and exhaust,higher flow ex manifold and a "proper" live remap. Even then i am looking at a reliable 270 ish.
I am not saying higher outputs are not possible, but how hard do you want to push ?
Ok this is on a B5 and B6 managment is better/cleverer so maybe slightly better would be available.
just my 0.2