18 inch rims

are there any problems with putting 18inch rims on my 2002 camaro
the 18by 9.5 zo6 rims.

and also how much faster will putting 3.73s on my 3.8 be? and the cost?

Well I don't know for sure how much quicker your car will be, but Jegs has 3.73s that fit in your 3.08 casing for $195

To answer your first question: NO, there will not be any problems w/ putting those wheels on your car.

To answer you second question: Yes it will help your Low-end acceleration. However, the 3.8 V6 N/A trim tends to fall flat on its face in higher gears--fourth for manuals and third for automatics. 3.73s will put you in those high gears quickly, so then when you actually get to the top end your acceleration will be decreased at best, butchered at worst. Additionally, with 3.73s your engine will rev quite high when driving at highway speeds, typically at 2500-2800 rpm. For periods of time this can cause excessive engine wear and terrible gas mileage. So personally i would go w/ 3.42. Just my .02

Hope this helps.