I am having difficulty believing that I have been flying stunt long enough to have been around for the whole pipe development history! I have never tried a pipe set up primarily for cost reasons. The way I have to pursue the hobby is to leave models hanging on the wall for long periods of time until the chance to fly presents itself, then I can grab a plane and supplies and go fly. The traditional muffled engine/uniflow tank set up is pretty stone reliable and dependable once everything is tuned and trimmed. Only occasional maintenance is needed to keep them peculating properly.
I do like to fly the different types of engines just for the experience. My main engines of choice is the newer ST.51 for large models, and this engine has served me very well over the years. As reliable as an anvil and very economical. Won my fair share of trophies with this engine. The same for the ubiquitous OS .35/40 engines and clones that have been available over the years. Again very reliable and economical to purchase and operate.
I ventured into the four stroke arena a few years ago, again, just for the experience. I got to a point where I undertood why some guys love them and some guys think they should all be melted down and made into something else. I finally started using the set up similar to what Bob Reeves uses, and some one on one discussion with Gilbert Berringer, and I started to have some success. One thing I had to do was forget everything I knew about engines and props (related to two stroke engines) and go a different route with the Saito I have been flying. It makes a completely different kind of power than what I was used to, and had to learn that and use the power accordingly. It's amazing how you become used to hearing and feeling things that you subconsciously (or consciously) relate to proper amounts and types of power!!

The Saito, when i finally got it where it worked like it was supposed to, didn't sound like it was making enough power to get out of it's own way, and like Brett said before, pulling up into the first wing over was done with some apprehension! But it worked. Then came the first loops in any kind of wind. When running 7 inches of pitch, that ingrained perception of what I have learned over the years about prop pitch had me just waiting for the model to speed up to mach 1 by the end of the third loop, but it never did happen that way. I guess that extra stroke where there is no power being made or delivered helps with the speed regulation or acts as a brake. Even just flipping it to start it gets interesting. You develop a rhythm after all the years of running two strokes, that just gets in the way of starting a four strokes sometimes!

I find the breed very interesting, and plan to keep one or two in my fleet, but I don't plan on selling any of my two strokes either.
I discovered the ST.60 a couple of years ago. Even though I had a couple of them stashed away, I had never operated or flown one. I had helped Chris McMillin with his in his Golden Falcon for several years, and had seen them operate in other guys models. But it's not until you get one in your hands, feel them operate and feel them on the end of a set of lines and handle that you know what they are like. Again, it's an interesting and different kind of power. Old fashioned, classic thumping kind of power! The one I have been flying in in a 72 ounce Cardinal that I bought with the engine in it. Once I got a prop working the way it should on it and got the big heavy behemoth flying acceptably, I packed up some good ST.60 cores that I had stashed and sent them off to Tom Lay to work his magic! I will definitely build a more desirable model for one of these some day!
The pipe has been interesting to observe over the years. I remember lots of flying buddies commenting about "going to the pipe" as we progressed up the skill ladder. Hoss probably relates to the pipe as he was exposed to it early on, and it is usually refered to as an expansion chamber. These are common on typical two stroke go=karts, motorcycles and such, and are typical on C/L speed models in that form. Most people in these areas are familiar with the term, 'getting it up on the pipe' and this is equated with what is called in motorcycle lingo as a "hit." And this is what i'll bet Hoss had in mind. And it's exactly what we don't want in stunt, and I'll guess that this was one of the early developmental issues of C/L stunt pipes, taming or eliminating the "hit."
I have never seen the inside of a carbon pipe, and they have really changed over the years, from what resembled a typical expansion chamber to the units in use now. And the engines , to my ear, seem to operate differently now than in the early days. So that leads to a question that l have. Were the early pipes shaped like a typical metal expansion chamber, and hollow on the inside straight through? and are today's pipes a series of chambers and baffles to regulate exhaust flow and resulting waves, and thus managing the 'hit" more successfully? I remember guys in the early days were always adjusting the pipe length. I know from my Kart racing days, that this was a tuning method and enduro type karts had a variable length pipe that one would adjust as you drove. Today, the pipe length seems to be a predetermined specification and is seldom adjusted. I almost think that 'pipes today are really just a very long sophisticated muffler, and that a lot of flyers that use the latest generation of high end engines are just using rear exhaust mufflers. I am just curious to know the theory and find it interesting, even though at my current situation, I doubt that I would ever invest in a pipe set up. When you factor in the current (no pun intended!) trend of guys going electric, there are many different routes a guy can go to fly stunt successfully, depending on what type of power and technology as guy relates best to and can afford.
Been enjoying this thread and bit of history a lot!
Type at youlater,
Dan McEntee