I have an ASP 1.08 that over the last year has turned out to be really reliable. I've had it on a .60 size U Can Do with an APC 15X4W and Byrons 10%. It's never really struggles with it or anything but I was only getting about 9200 RPM out of it. I've read through some of the things guys said about them and I guess that's about normal. Well, I decided to put that engine on my Ultimate and was looking for another prop to put on it. A 16X6 Zinger would turn about 9K, but an APC 16X6 would only turn 8700. Well, I was flying it around with the zinger when all of a sudden it got really loud and wouldn't run much faster than an idle. I got it back down to find that the muffler had come apart. The nut fell off and the baffle was missing, but the back half of the muffler was still in the cowl. I took it to work and welded it back together. I fired it up and retuned it but it didn't sound right, and it wouldn't idle with the Zinger. I've taken the baffle out of some of my smaller engines and didn't really notice much of a difference. I put the tach on it and I was getting 11700 RPM with the zinger. I put the APC on it and it idled a lot better and it turned 11400 RPM. I have never seen that much of a gain by just removing the baffle. I had it up this afternoon, and the throttle response is almost that of a 4 stroke. From idle to WOT in about 2 seconds. It had my 10 pound ultimate airborne in about 15 feet. It's a totally different engine. My mixture is good and rich and everything seems normal. I don't run it at much more than 1/4 throttle for now because all the posts I have read say to keep it under 9500 RPM. It's not the red head, it's just the plane Jane series 3 stock engine. I'm thinking I could probably go with an 18X6 wood or 17X6 APC and it might bring the RPMs down a bit. Is this normal? 3K RPM gain from removing the baffle? I bought the engine used, so I can't say for sure if it was the origional baffle. It was flat and had slots cut in it. Most of my 2 strokes are OS and SuperTigre. This baffle didn't look anything like either of those.