people i talked to say injectors, right turbo 200 before pump mods with a rover pump...
libby is a member here who sells/builds pumps.. his i think are cummins based vs rover based.. they all bosch just different brands use..
mine (rover w/gov mod)with real ic, exhaust, stock silly little turbo, finally cooked it, was more then enough to tow car from cali to ohio.. as i said.. i think its more stout then a 2.0 16v.. and running too much boost stock vr6 no issue.. mine pulls 6k rev like gasser too.. and its pulling.. not dead..
why did mine eat turbo.... somewhere i popped a coupler.. still made 15psi at manifold.. how much over spool? also hit a egt of 1450 for 5min thru mountain passes on west side of denver... those 2 things related, who knows.. had 305k miles on it and ive run it 18-21psi since my build.. those little kkk not supposed too... mine liked it..
yours is bigger so a power upgrade.. you just gotta find a tdi long block.. i suggest a 02a conversion.. a libby/rover pump and bolts in like yours is..
if you go with a serp alt set up.. the ic room becomes less..
what i would do in a non ac mk1 is side by side intercooler/rad.. make them thick and skinny.. just your alt set up will determine width of it all...