none as long as you dont try to make too much power (for 99-04, the max is about 420rwhp, im not sure about 98)...MAKE SURE you get a good tune also.
most of the problems come from a crappy tune that ends up destroying the motor...
later on, you can look getting a new shortblock(piston rods are the main thing that blows, but it would be good to have the whole rotating assembly forged which usually can withstand up to 650 hp)