Sorry to say but I have 2 pics of it in 2 different RC Mags that clearly show no Belt tensioner. Also I have a pic of a TRF414MII used by David Jun with no tensioner on it as well.
You work it out
The best thing for you to do is try the car without tensioner and see what you think.
I found not using a tensioner on My TA04R and Xray had no negative effect at all.
The best way to learn is to experiment with your car and see what suits you best. By testing these things you get to learn about your car more. Its not going to damage the car in any way so give it a try and make your own decision.