Hi wlevey, just got done with the latest mods to my '02 Sirrus A1 Sport.
I was also unhappy with the rear cogs, so my LBS put on a 12-25 cassette for me. They were also kind enough to adjust the derailleur for it and mentioned that a 12-23 cassette probably wouldn't have worked with the OEM derailleur. The mechanic showed me the clearances (just barely enough) with the upper adjustment screw backed almost all the way out.
It was an embarrassing experience as I had just had the bike tuned up and was talking with them about installing the 8-speed 12-23 cassette I had ordered from Nashbar to replace the OEM cassette. The mechanic looked at me kinda funny and asked if I was sure I wanted to downgrade from a 9-speed to an 8-speed. When I told him I was going from an 8 to an 8 with a little less hill climbing ability, he said wait a minute we'd better look over my bike and see what I really have...
We found out that my Sirrus came with a 9-speed 11-32 cassette. The shmucks at Specialized claim the cassette is an 8-speed 12-25 when it is in fact a 9-speed 11-32. Specialized also sez the Sirrus comes with 52-42-32 chainrings when it actually has a 48-38-28 (can't remember the exact numbers but they are nothing like the 52-42-30 claimed on the website).
I should have known better than to order before ground truthing the specs first.
Now, thanx to my LBS (who gave me a good deal on a proper road cassette and installed it free), I've got a bike that's better suited for the road, with parts that fit and parts that work! I really like being able to fine tune the gears to get the best performance when dealing with wind or hills. I lost a little top-end and bottom-end ability with the smaller/tighter tooth count, but I never used those gears at the extreme ends of the OEM cassette anyway.
Oh yeah, I also took off the OEM stem and replaced it with an adjustable ATB stem. Now the ride is much more comfortable.
To see a pix of my steed, click here.
Well that's all for now, hope you're having fun riding your Sirrus somewhere!