I wouldn't say the SS is the best bar none... even though I'm happy with mine, there are some nice engines out there. The P-100 looks very promising. There are other 18-20 pound thrust engines too. Look at total installed weight. The P-100 doesn't have all the extra stuff like fuel and gas solenoids, everything has really been cleaned up and the kero start is probably worth a few ounces of weight hit in convenience. Make an engine choice for this model primarily but also look at your next jet too, it's not super critical. Don't sweat a few ounces here and there as long as fuel burn is good.

The 2 biggest things I can say that will save weight is 1) the engine choice and how you mount the engine, and 2) careful planning to mount as much stuff in the nose as humanly possible. I mounted my engine very far forward. Not just forward on the rails, but I modified the forward engine mount rail rail bulkhead to accept the engine stuffed very far forward, much more so than an unmodified bulkhead will allow. I also modded the ducting to accept the starter housing and FOD screen. I had to have Tam make me a custom pipe for this though - the P-60 pipe isn't big enough for the higher thrust first off and second the length had to be longer to accept the forward position so the P-70 pipe wasn't long enough either. You may ask, "how is that going to save me weight if I use a heavier engine and just mount it forward; the engine is still aft of the CG isn't it?" Because the stock position for the P-60 vs. the modded position of my heavier engine actually favors my heavier engine as far as CG moment arm and counter weight required in the nose to attain CG. It will help. Do not be tempted to put your UAT in the nose though. If you somehow get air bubbles in it you are going to crash and not know why (major aft CG if you get air bubbles). My UAT is part of CG ballast but it's not so critical, it's located on the right side just aft of the canopy opening and equipment tray.

Make your nose equipment tray permanently mounted to the airframe. The nose cone will just be a fairing that is removable to service the batteries, fuel pump, etc. The permanent mount forward tray makes it possible to stuff a lot more equipment up there; it really moves installed weight forward. I use twin A123 2200mah battery packs for the Smart Fly battery bus. My FADEC battery is in there too. Even my solenoids are in the nose. I don't have an on-board starting gas tank, I have an off-board one. I use a festo quick disconnect and a manual on-off valve that arms the tank for the normal engine auto start. This saves space and reduce crash fire risk (debatable). That also saves me about 5 ounces of tubing, tank and mounting equipment. It all adds up. The biggest weight saving for me is I have absolutely zero lead in the nose. Some guys have nearly a pound of dead weight in the nose. My install is not quite as pretty, because it's really crowded in the front end. But it's effective - where it counts is when the engine is running. I also am using Tam's personal CG position of dead center on the forward wing tube. That's just a little aft of the normal CG position Tam shows. I find it suits me but I'm not telling you to use it, you'll have to make that choice. But that allowed me to take out all ballast I originally had (a couple ounces only).