I'm using the
TST 507 with flow thru sensors. A few things to watch for with any TPMS:
1. The plastic rear valve stem extenders FR used on our GTS were junk to put it politely. I couldn't even add air to a low tire thru them.
And you cannot use a valve mount sensor on them. I highly recommend going with a set of one piece stainless steel valve stems from Duallyvalves. We have a E-450 chassis so I used the DL1FCR kit shown
Here. When I called to place my order I had the front stems upgraded to a stem with a bend for easier access.
2. If you have the "wheel simulators", as in the big stainless hub caps, you may need to notch them to use any sensor. You will definitely need to notch them to clear the anti-theft devices on the TST non-flow thru sensors. The anti-theft devices can be removed which is what I would do if I had it to do over. I remove the sensors while in the storage lot anyway...
3. I started off with "regular" non-flow thru sensors. Having to remove them to add air to the tires was a PITA. Last year at the FROG Rally I upgraded to flow thru sensors and I'm a lot happier. This is really a personal preference issue, both types work...
4. With the TST you want to change the sensor batteries annually, as in each spring for me. If not you can get some really weird readings as the battery runs down...
Hope this helps...