Hi 2lo,

I just found this out myself recently. The TSS is basically a custom version of the TS. In other words they will custom build you a version to your specs....port timing, polishing, compression, intake, you name it and they will do it for you...of course it won't be cheap, but it would be a really cool one-off motor. It's a service that's tempting me, even though I have no good reason to do it except that I love motors.

I have no idea why they show a weight difference. You'd probably have to ask them.

For an example, this would be a great service for someone that needed a race engine built. For typical R/C applications there should be no reason to need one of the TSS's.

Bill