A little history from my local track:

One of the members bought a BTT last year from a LHS (parallel import...). There was a fault on the tip of the crank (due to the loss of the motor on the floor???). Because of the parallel import it took several moth to get a new crank...

The member maaaayby hasn't the biggest patience, so the break-in was done as follow: 3 tanks of fuel in break-in bench at idlespeed. It was done in the winther time and the engine never reached 85º C... Then into the car and off to a practise weekend. The ambient temp was approx. 0º C all weekend. Without a sock, alu tape etc. around the head, he started leaning the engine after the very first start at the session. Screaming lean all weekend...
Some month after he started racing on our outdoor track and he really hated the mill... It was impossible for him to find the right tune, so the engine kept flaming etc. etc.. We told him to stop those 1/8 to 1/4 adjustment on all screws, because he would never get the tune right... He never listened so he finally gave up, and gave the engine to another member... for free! It had only 2 3- gallons on it.

Without ANY part replacements the engine is a killer on our track. The new owner has 100 tanks of fuel through it so far. When he got it, he put in a new C6TGC plug in. That plug lasted 90 tanks of fuel... ... I tried to convince him the try a 9901 or RB 2045 pipe insted af his 2057 with an insert so he could get some more topspeed... But he is happy as it is, and thats just fine with me

BTW: The new owner has been racing Sirio engines for the past few years. He is impressed with the Novas smooooth powerband - much easier to drive the car...