Engine tuned
No EB is selling a tunned Extech Trinity mill. All other mods are not bench broke. They just re-mill the internals and put them back together and runthem out the door. You will still need to break most of the motors in and tune them. If you are not an experienced tunner. It really pays to have a pro tune the engine out the first time. To pay for extech and this service will save you a lot of personal time. That is what make the engine most attractive to me. By the way any of these engines are good, and you will not feel bad about owning any of them. People that live in unfriendly Nitro environments generally prefer engines that are easy to tune. When I race there are many times you have 100F heat and 99% humidity. Engines need to run really lean. From morning to mid day Temps and humidity can change drastically. So you will have to retune during the day regardless. Again if you do not like the final fine tunning process then pick one that is easy to tune. You will get more power out of any tuned engine over some engine you feel you need to run fat because that you can not eek out that last 5%. NR, higher RB, GRP. O.S. engines are really easy to tune and the stories concerning their rear bearing are greatly exagerated. Several people love them at my track, and would not drive anything else. If you are worried about it then spend an extra $20 and get the new Ninja JX. Me I will stick to my NR.