I think these engines are very good quality for sure. I had one of the first gen's in the summer of 08' and like it a lot! But I've heard these new ABI's are not getting the mileage.. I had heard that putting a grp carb will do the trick...and I think its true. A buddy of mine just got the ABI a few weeks ago and was only getting about 7 1/2-8 min.. He took his old carb off of his old ninja(not the jx) and bam.. 9-9 1/2 min. But I'm still looking into getting another one as soon as my Werks is done..
I believe that some people are running the GRP carb because the Orion has a tendency to stick if not set-up properly. Runtime depends on driver, track, tuning, etc.. My .21 gets 8:30-9:30 in buggy and the .24 gets 7:30-8:30 in truggy. Both running on 2013 pipes. Still haven't tried the .21 in the truck, but it should get 10min.
Personally I love my Orions, they are very well built and stubbornly reliable. I sold my Nova after running one for the first time.