I just ordered an xbr/13.5 combo and was wondering how much faster will it be than stock? also, is the upgraded rotor worth buying?

Look up the results for Oval Masters, any BRL race or ROAR paved nats for a comparison to stock. In short, a lot faster than stock. If we're talking flat carpet it'll be in the 3-5 lap range depending on relative talent level and race length.

Yes, the sintered rotor is worth the $30. It runs a lot cooler and ultimately is faster.

At my home track it was within a lap of 19T... Wingless BL13.5 versus winged 19T open..

On our track 13.5 is running close to speeds of the 19t. The track is 365'. Checkout the laptimes from this past weekend's race

http://focars.net/2007JAXresults.htm

thank you guys.... I am trying to generate an interest in brushless at our track and this seems to be a good way to do it. I will run it in stock for a while and then maybe we can start a class

Charger if for you track is looking for more stock-like speeds from a BL motor try starting a 17.5 class. They seem to be about a lap quicker. Brushed stock is quicker up front but 17.5 over the course of the run doesnt have as much drop off.

thank you guys.... I am trying to generate an interest in brushless at our track and this seems to be a good way to do it. I will run it in stock for a while and then maybe we can start a class

Honestly we have been mixing the stock and 17.5 and they seem to be fairly close.. e-rock is correct..

agreed, if you try to mix 13.5 w/ STOCK..once you figure it out the 13.5 will be MUCH faster.

The 17.5 will be really close on just about any type/size track.