I'm looking for the type that set in the top of the tank and are held in place by the gas cap, also which ones do you recommend? I've been searching TT and online Google and only been able to find a couple places that make them. The most common one I find is the Twin Air but it seems to have poor reviews. Splitstream seems to have good ratings but they don't make one for my bike (13' WR450). Any help would be appreciated, thanks.