i'm for sure you're right they are all made by novarossi. But they are different. I'm not a builder so i can't tell what is different about them - but something is because they run different. I have an rs12 turbo, it's more a top-end motor that needs to rev. My rb x12 3 port has the same specs but is much more punchy off the bottom. I had a mugen mt12 - it had the most punch of the bottom of any of them - but they're all novas. Maybe the timing is different - I dunno - maybe the experts around here can tell you.

I cannot say that the other novas are any less or more reliable than the RB, because I have not ran the dog out of them like I have these RB.

Basically I have some 3 port x12 turbos and I came across an awesome deal on 5 port piston/sleeve's for them. So I've been trying to my darndest to wear one out so I can put the 5-port sleeve in - problem is it just keeps getting better.