Would it work stuck to the floor, between exhaust pipe and floor?
From where did you buy it?
it works on the pipe just fine, on the cat is the problem, it still screens but not as efficient as on the pipes where's there's a bit of space between the mylar fabric and the metal (they have some risers that keep it away from the pipe).
I bought them on Amazon, they are made by thermo-tec, 2 of the 3ft ones would cover the downpipe and the cat the way i have it, but i ended up with a 3ft, a 2ft and a 1 ft that i bought later from a local store (price was a little lower at the store so better if you can find them locally), i thought the 3+2 would be enought, wish i would have gotten a second 3ft rather than the 2+1, however it makes it easier for me to take the downpipe out by removing only one clamp (4ft + 2ft would be ideal but i don't think they make a 4 ft one)
here's the link for the 3ft one, it's a pretty good picture to understand how it works, idea is to keep it away from the pipe, screens the heat really well, the pipe is extremely hot even with the lava wrap but you can put your hand on the aluminized side of the screen and keep it there no problem
http://www.amazon.com/gp/product/B000GVQZ8Y/ref=oh_details_o03_s00_i00?ie=UTF8&psc=1