well maybe there was one with a GN motor but i mean u know enough about cars to see the point i’m tryin to make… 245hp is the advertized stock HP in GN. most Turbo buick experts will say its more like 275hp… 275hp in a gtp isn’t even crackin 13’s. lets assume you meant no internal mods instead of “no motor bolt ons” you would need a large turbo, t-60 and up with all the supporting mods (computer, injectors, beefed up trans, axles, fuel pump, wastegate, exhaust, IC) the car itself would need to be on a serious diet to touch the middle 10’s.im sure et10sec can tell u it takes a lot of the right combination of stuff to get a GN into the 10’s. once you get into the 10’s the stock block is gonna go poof real fast unless you have modded it. I would say guys dipping into the times you mention aren;t even running “109” blocks but are running stage 2 blocks.