Jet Engine Bike is back! 10 donut refund

"Excruciator69;c-1644402" wrote:
Jet Engine Bike at a ten donut discount is the Holy Grail of bang-for-buck multiplier enhancement.

Is that correct?

Thanks!

"Short answer yes with an if, long answer no with a but...."

Still a subject of much debate here, but in my experience (and others) the mystery boxes long-term average are still slightly better at an average of 8 donuts per 1% increase.