alot of people here have tt's, including myself. Theyre not needed on our cars because of the prevoiusly posted reasons. I like the convienance of letting my car warm up without the key in it, or running into wawa. I wouldnt bother with one with an afr gauge, if you want it, go get a real wideband sensor and gauge. And i would also recommend against using vampire taps, they generally suck. Strip the insulation back, poke a hole through the wire, slip your new wire in the hole and wrap it around, then solder it and tape/shrink tube. Thats the way i do it. Anyway, i say go for the tt if you really want, just dont bother with the afr.