I entered the nitro scene this year and got a Novarossi as my first engine. Bought one due to its reputation for quality, performance and longevity. Just starting my fourth gallon on it and am extremely happy with it. No issues of any kind so far. Once broken in correctly there is minimal tuning needed on a daily basis. They may cost a few dollars extra but are worth it in my opinion.
Got mine from Houstons Engine service. Search the nitro off road section for him. Good prices and top notch service and advice. I will buy from no other source. Monty is the man.