Probably one of the most important differences between the pro and the regular kit is the upgrade to TRF shocks. You also get an aluminum motor mount, aluminum turnbuckle shafts, and steel universal driveshafts all around.
The TRF dampers are wonderful but the springs are something to be desired...it's too soft. In my first rally race on tarmac (medium grip) with patches of sand, there was too much body roll and the chassis was too mushy. Trust me, it looks realistic and cool as hell but man it was painful to drive. On hard turns the back wheel would actually lift. Stiffer springs and/or anti-roll bars could have helped here.
So before my second rally race, I purchased Tamiya's On road tuned hard white spring set part# 49382. For low grip offroad I installed the soft (reds) in the rear and medium (yellows) in the front. Used the stock damper oil that came in the kit all around...I think it's Tamiya #900 wt. Wow what a world of difference over the stock springs. This upgrade is a must!
It was responsive but not jittery and soft enough for traction on snow/dirt/asphalt (surface type I raced this past weekend). It was easy to drive. An easy driving car is a fast car. To me it felt balanced.
This is my first belt driven car and it's smooth and quiet compared to shaft driven vehicles which means something to the quality of this product. The mud fenders are an excellent touch, the semi-sealed esc and rx compartment is excellent, and the sealed silicone filled diff is wonderful. Building the pro kit was fun as was my other Tamiya kits.
Now for some of the negative bits of this build. Tamiya couldn't completely pimp out the pro kit loaded to high heaven...they won't make money that way. So what broke on my XV01 this weekend during one of my races? My drivers side front suspension mount broke (made of plastic!). Tamiya conveniently released aluminum versions 54379, 54376, and 54377 (for the rears). So I'll be upgrading to those as the plastic ones will be too brittle for racing in the cold (-5 C).
Bulky aluminum parts are quite durable. However, in non bulky form we found that aluminum turnbuckles are not suitable for jumping in cold weather. One other racers XV01 turnbuckle broke after some light jumping. He was very upset. So if you are doing some serious jumping or running in cold weather, I suggest using steel turnbuckles.
Other than that everything is great on this car. Use the right tires for the road conditions and fine tune the suspension and you got a great rally car and could make for an intermediate on road car too.
Also, if you're doing hard running and jumping with this car, get the Tamiya slipper clutch set 54378. Note that the slipper is 77t and the stock it 68t so you'll be losing some top end speed if you don't change to a larger pinion.
Out of the box using a 17.5T on 2s lipo with the stock gearing (22t pinion/68t spur) was a bit slow. So I ordered Tamiya 26t and 27t pinion set 54228. The 26t was perfect for rally on snow/dirt.
Comparing to the DF03ra which I also have, they both are comparable in performance. I know because I raced a couple DF03ra's this past weekend and they are still a great car. But the XV-01 is something new and I had to have it. The front motor position is something unique to me and I must say that I like the front weight bias. It's a different driving experience for sure....meaning a positive one.
Overall, I'm more than happy with the XV-01.