I have 2005 gtr with a stage one and started noticing a drop in my top end used to run 29-32 now only getting between 22-24 running 3850 rpms. Would a worn down prop cause this?

Yes

Worn prop, hooks in the boat, OR you just got REALLY fat.

Worn prop usually means more rpms.

If prop is good may want to do a leak down

Picking up fat chick will do it too

Check your throttle linkage to make sure you are getting full travel.

If its still the original prop it came with, Ive got 20 on a worn prop.

No i didnt get fat. No i didnt pick up a fat chick. No it is not the orignal prop i got a new one 2 years ago normally would get a new one every year but didnt really use it much last year so didnt think it was that worn but pulled a measurement yesterday and prop was 11 3/8 so that is prolly my problem gonna put steel flex on the bottom this week as well as get a new prop or have my old one rebuilt. Thanks for the input though.

If you have a worn prop and still only turnin 3850 with a stage 1 motor (I'm assuming that is with an empty boat) then your valves are more than likely leaking as well

You have other issues besides a worn prop. My motor is stage 1 and I turn 4600 rpm.

How hard is it to check the valves, what do i need to check the valves and what is the tollerance supposed to be if yall dont mind me asking.

Also did the gear ratio change from 2005 to 2010. Reason being i went from a short transom to a tall transom in 2010. If so could that be why i am not getting the rmps that i used to get??

Your ratio is going to be in the pulleys, did you get a new lower unit with the belt housing/new lower pulley?