I have had many 3.3s. No problems with any of them, so I think they’re good engines.... They just need a little work to really get them to open up. I’m currently in the process of doing a mod job on a new 3.3 built from spares. One thing I did do was swap out the stock Traxxas rod with the replacement rod made by Sirio years ago. They made all sorts of parts for the 2.5 Traxxas engine; however the rod was the same between the two engines. I’ll have videos posted on YouTube of the hot mod 3.3 this spring.