with a stock TB I would recommend over 25%. Otherwise it'll break loose when climbing a hill or just randomly. I have a N* and mine is set to anything above 25
2003 GT Limited Edition 199k - The $600 winter beater. 2004 Buick LeSabre 172k - Top Swapped, 3.5 pulley, 1.9 rockers, SLP headers... still slow... MAKE AMERICA FAST AGAIN!