Just as 60-1 said, once you have hit your goal, you are no longer satisfied with it, you just get used to it and want more... Its like liquor... Every time you drink, it takes just a little more to put you where you want to be... This shit is addicting, and all you will ever want is more more more, until you just cant go any further...

Besides, where your goal is now, I would reccomend it anyway... I say anything over 400whp, you should sleeve it... Ive seen 500 on stock sleeves, BUT, the fear you have of "when will it pop" SUCKS... Trust me!!!! Just sleeve it with a good piston and rod combo, and never have to worry about that dreaded drop in oil pressure that comes right after that loud pop...