KR isnt bad, KR is good.but that's besides the point.
do not drop any pullies. find someone with a tuner and tune for more timing on your stock pulley. it will feel retarded faster after doing this.
keep the smaller pullies in mind, but dont get pulley envy before you have enough done to run one safely. honestly, i think it would be fine for you to run a 3.5 so long as your gas pedal doesnt have two positions, but then again youd probably be knocking a little too. it wouldnt be anything crazy that would kill the motor anytime soon, but eventually you may see some damage. it only takes one wicked blip of knock before you chip a piston.
for now, keep the stock pulley on until you have some exhaust work to help with the flow. if youre interested in getting a u-bend delete, then just get a 3" downpipe while youre at it and then you can think about dropping that pulley down to something like a 3.6-3.5. otherwise a few little tweaking mods beyond the downpipe and you could potentially run a 3.4 just fine and the 3.4 pulley is what most people go for in starting their modding. its the pulley size that really makes the car start to move.