I've been looking at changing the front sprocket on my Marauder. The folks on the Marauder-Intruder board highly recommend it mainly because the Marauder's RPMs at highway speeds are kind of high. Here's some info I found:
5th gear rpm @60 mph are:
15 tooth - 3884
16 tooth - 3641
17 tooth - 3427
And a nice quote:

5th gear rpm @60 mph are:
15 tooth - 3884
16 tooth - 3641
17 tooth - 3427
And a nice quote:
Bear in mind this very Marauder specific