Compliments of Eikoms, a Japanese Rotax distributor, comes one of the first on-track reports concerning the relative performance of the Rotax Evo and "Prevo" Rotax Senior packages.

Roughly translated to english, it doesnt go into great detail or cite data, but it does give the impression that the Senior Evo and Prevo packages are comparable in performance. Junior testing results still to come.
H/T to Larry Hayashigawa for the link.

Because the first EVO engine (Senior) arrived by extraction in random, Mizunami circuit, we tested in mid-Kyushu circuit.

Thank deeply to everyone you cooperation. 

Sequentially, our plans to pay conduct also test / test drive in the other circuit. 
EVO engine, conventional engine, we compare the specifications that various combinations of conversion kit to a conventional engine. 

Differences related to the engine body was not at all performance difference, even taking into account the state of each of the engine. 
Notably, EVO engine hardness is not felt much immediately after break-in, I was able to experience one of the improvements. 
Carburetor, ignition, even in each mounting comparison the conversion kit of the exhaust valve to a conventional engine, 
but was not able to find a difference in lap times compared with conventional engine, 
if the new carburetor is mounted, improvement of pickup clearly observed, it will not require a delicate accelerator work. 

The lap time basis, to you, but there is a possibility that put out the time is more easily same. 
For the exhaust valve, since the opening and closing at predetermined rotational speed (7900rpm or 7600rpm) to digital, 
and the conventional exhaust valve which controls the analog opening and closing, the difference seems out but performance specific to differences in In the setting that it was not able to find. 

Although it is not a strict comparison because there is a difference that new and used also in relation to the muffler, the conclusion that either dominates It was a level that does not put out. 

The new muffler seems durable mounting method has been improved is improved. The RMC race of 2015 is based on the above test results, I will assume that the provision of the following such rules. * Senior class, in regard Masters class, EVO engine and conversion kit (harness, exhaust valve, muffler), but the use of I do as possible from the opening round, 


* Regard Junior class, we will as soon as possible to your report after the confirmation test test equipment arrives. 

Ltd. glory Representative Director MatsuDo SakaeMakoto

Source: http://www.eikoms.com/Info/2014/20141227_Test.htm