The Webra 12 that I have is a jewel. Rear exhaust and ball bearing and pricey at $129.95 when I bought it. The muffler was extra as it did not come with the engine. Power was there and would keep up with most of the decent sport 15's of the day. Somehow or another I lost the needle valve in storage and after 2 years of trying to get a replacement I gave up and converted it to a control line engine. I really need to find a design that moves me to get this little jewel back in the air