YellowAircraft and bvmjethead:

Both of you have a good and true point. I`m just sharing my experiences and what I have.
Regarding a VIOFAN it is an excellent choice but must go with BVM engine ( my opinion) not with OS 91 either way could work, period.
About testing I made at home in my bench, it was just for fun and have a comparison point.
I have a RAMTEC that works great with a Rossi 90 and also I set up for a couple of customers DYNAMAX one with an OS91 and JMP pipe and another with a Rossi 90 modified, and bot are performing well.

Again an in deferents words and with my elemental english, if You have a Ferrari I assume you will have a Ferrari engine ( VIOFAN AND BVM engine) if you have a Porsche you should use a Porsche engine(Dynamax with OS or Ramtec with OS or Rossi 90)
Maybe you can use a Porsche engine in a Ferrari or vice versa and maybe will work for a period of time.But something will happen at any moment plus all involved in trying to swap parts correctly.

I`m not an expert like some of you guys and think this kind of post are all time useful.Most of the time new people is coming here at RCU to learn. Is like a school. I personally learned a lot during last year just reading posts and helping others setting their DF before having my own.

Miragepilot: I don't have data that proves BVM engine will over-rev but if Rossi does, BVM egine will do much easier. I promess will try and will let you know.

David P.