Made my self a custom bump seat. Sorta like a quad tech for less then half the price.
$50 for the factory effex grip seat and $2 worth of foam. Doesn't look to bad either.
I used some 1 inch thick garden foam knee pad blocks for mine. Ive heard of people using other things such as foam bar pads, heavy foam, ect. Depends on what style your going for some will work better then others.
Sitting on the quad in a aggressive race stance i measured how far back i was from the end of my seat. This is where i decided the bump would start. Found that a packing knife worked great for cutting the foam. I did my best to follow the flow of the seat and make it blend on the sides and rear. For the front part of the foam (facing towards the gas tank) i cut a bit of a dish out for some added comfort :macho Lots of dry fits and shaving i finally got it how i wanted it to. Traced out the placement onto the seat and crazy glued it on. Held it down firm following the lower rear part of the seat until dry. I then went crazy with gorilla tape (same thing as duck tape). I found out later that any little ripple in the tape will show through the seat cover. Now for the seat cover part it is a time consuming operation with the hump. I found that starting stapling at the hump worked best. Worked my way to the back then proceeded back up to the front.
Overall i think it turned out pretty good and for the price i can deal with a few hrs work :)
