Corrugated tube

Assuming its the black plastic stuff, I would just cut it. You can put the second half up under the first and it will still slide as if it were one, and you can use them separately when you dont have enough speed.

corrugated tubes suck i reckon you should burn it !!!

yea you definitely need a lot more speed for corrugated pipe than smooth pvc. Not really much you can do to speed it up. I suppose any sort of lubricant would help a bit, but it would still be considerably slower than a smooth pipe.

I would cut it into two 10ft lengths as well as get a smoother sliding rail also

Corregated tunes slide significantly slower. Cut it in half. Also get a fatty tube that isn't a corregated tube. You'll like that way better

I guess PVC would make it more better. Waxing it could also help.

I might try to build a frame to kind of hold up the beginning so it's slanted. I figure I'll have more momentum if it's angled down

Corrugated pipes can be pretty rough especially in a backyard setup where the ridges get full of snow and ice. I do like the idea of cutting it into two 10 ft sections though. Not that it would help you slide any better but it would be fun to configure flat downs and down flats and so on. But if you wanna slide better maybe try waxing each of the little ridges before you ski it. Besides from more speed I would guess that would be your best option. For when it's really cold you could even spray WD-40 on it. I know that's some pretty improvised stuff but It makes the plastic pretty slick. Good luck man!