I love it, honestly. The engines have a great sound, at least to me, and I wish I could put that jet in more things. Seriously, I love that thing, and would love to have a 2-speed, jet-powered Burnside just because I love the sound and the power. Heck, I'd settle for a single speed like we've already got, especially if that jet ends up in more cars. Or, if not exactly that jet, a lower-powered one for more cars to use.
I think my other favorite is the V10. It sounds mean, revs a little higher than the base diesel, feels like it's about the same on power, but makes an awesome delivery truck out of the T-Series.