If these are the single piece plastic one, I think you'll be unhappy with them. Even if you get them fit in there, the real problem is that they're non-porous. That is, they don't breath. Moisture from your skin has no where to go and ends up softening your sking. Meanwhile, engine vibration conducts directly into the seats and between that and the moisture, it'll rub the skin right off your back, right along your backbone.
Before you use these seats, go rent a kart for an hour - they have the same kind of seats. Your back will be rubbed raw.
Oh.. see now you hit my weak spot for fun.. I LOVE KARTING!!!! I 1st went karting in Germany and spent nearly every available hour in the Kart track down the street from the hotel. The guys thought I was a hermit, until they figured out where I was going then they all wanted to join in!! I was actually in more discomfort from the cramped position of my legs than the seat!
I planned on making a Goretex covering for them so I'm not too worried about moisture and while at it was planning on putting in some extra padding to make the long drives a bit more tolerable.. Paintball has taught me a lot of lessons about moisture control and padding, so I plan to put the skillz to good use!!
If there is no known way to do it other than cutting it, at the price I got these for, I may just go at it with a heat gun while tensioned and see what comes of it! What's the worst that can happen? I end up with a malformed seat and I get to try it again.
I got them to fit without cutting them.. I was just hoping to find an easier method to move them in and out of the vehicle!
Thanks for the warning though.