SRX's have triple pipes & power valves. 98/99's are roughly 135 hp & 00-02 are 140ish.
SXR's are single pipe & no powervalves. Not really positive but somewhere around 110+/-.
Not to diss this forum, but if you go
here & just search threads, you'll learn a ton about each type. It stays fairly active in the off season too which is helpful if you're wrenching on your sled & have questions.
You'll learn that peeps tend to swap parts off both types of sleds to try to get the best qualities of each...suspensions, pipes, etc.
I see you have the sx-r. Depending on alot of factors: tuning & set-up, rider skill, conditions, etc you may keep up with a srx off the line for a few, but it will soon be obvious of the power difference...especially when the PV's open up. SRX's have long legs & it seems like they really come alive at 60-70mph...they just keep pulling well over 100. Their stock downfall for trail use is the limited suspension travel. You'll notice their stance is considerably lower than most sleds...which helps on high speed lake runs but can be a handful in rough trails. Your sled stock will handle better in the rougher trails, I believe it has 11.5" of travel in the rear vs 8" on the srx.
Welcome to the site.