[ILLusion]

1) I use to build gearboxes all the time. It's a lot of headache, a lot of sweat, a lot of tears, a lot of cursing, and a lot of money, but when you build a really nice gearbox, you can't help but smile at the result. If you do it RIGHT, it will be satisfying. However, it's been a while since I built a complete one from the ground up, because it's just been more economical for people to just buy a pre-built gearbox. Even a high quality complete Systema gearbox is cheaper than trying to build one yourself from mediocre parts. And Pro-Win gearboxes are nice... but unless you have the need to do quick spring swaps or have the ability to split your gun in half, it's added expense. A Pro-Win setup completely upgraded with top-of-the-line parts, including installation labour can easily run you over $1000. That doesn't include the metal body you'll need to get for it. Labour will include hacking up your metal body to accept it.

2) If you go ultra high torque, you're going to have low ROF unless you use very high voltage battery to counter the ROF reduction. If you have low ROF, then you will also have high trigger lag. Trigger lag is a function of how fast the gears rotate, so if your ROF is low, you're just going to have trigger lag. You can't have low trigger lag AND low ROF.

3) For your velocity, most mechbox shells are fine. Unless you're after some particular feature (such as quick spring swaps), then there's no need to get them. You'll be fine with the stock Tokyo Marui shell up to 380fps. Otherwise, the price goes up dramatically, especially if you get a Pro-Win. (note: I don't think Modify gears will fit in to a Pro-Win anyways)

4) Yes, get a polycarbonate piston. DON'T get an aluminum piston. It's very rare to see aluminum pistons in use nowadays because of the numerous downsides they carry. Don't get a piston with aluminum teeth (do they even exist? I don't think they do.) Half the teeth being steel is fine. I like the Prometheus oness, I've never had a problem with them, but they are pricey.

5) Piston heads: Get a synthetic one. No metal piston heads unless you have a gearbox that can handle it (Pro-Win.) I've personally always liked the Systema Silent Head Sets, as they're the most performance effective and overall most cost effective for combined damping power and performance. If you want the ULTIMATE damping power and truly silent performance, get an Angel silent head set. The damping performance of the Angel silent head set is miles ahead of any Sorbo or Systema solution.

6) Modify spring guide should be fine. It's really hard to get a bad spring guide.

7) No need to match brands on cylinder and piston. Systema cylinder is a good baseline. Modify ones look okay, but I haven't tried them. Prometheus ones are expensive, but nice. Top of the line ones are KM TN taper cylinders, which are really nice, but expensive. They have minimal friction due to the lack of any porting on them, as well as KM's patented TN coating. No need to get bore up. It is not necessary for your application, just get the cylinder size appropriate for your length. (450 mm is close to an AK-47, which is 455mm). More expensive ones have ribs that act like a heat sink to dissipate heat built up through friction in ultra high ROF setups. Coated/plated cylinders last longer and are less prone to oxidation such as the standard brass ones. Although, a really expensive one versus a standard plain jane brass one will perform pretty much exactly the same in the beginning. However, as a brass cylinder ages, it will lose its luster and shine and the polished will become rough and scratchy. It will affect performance.

8) Air nozzle: I recommend to always match brands with the cylinder head

9) Can't really go wrong with the tappet. Modify is fine. Systema is fine. Guarder is fine.

10) You can't go wrong with your selector plate. Prometheus, Systema, Modify all have low resistance ones, but it's not necessary for your setup. It will not improve trigger lag. If anything, get an aftermarket one that has a wider bearing channel to accept 7mm bearings (if you decide to go 7mm)

11) Sector gear clips will not slow performance down. It just changes the timing of things a bit. I'm not even sure if you can install it inside a Modify gear cage. All sector gear chips are used for is if you have an ultra high ROF setup, it changes the timing so that the nozzle is held open for a fraction of a second longer so the BB can reliably feed in to the chamber before being pushed in to battery. It helps reduce misfeeding in high ROF setups.

12) Wiring: The lower the AWG, the fatter the wire. The fatter the wire, the more current can be pushed. The fatter the wire, the less the internal resistance. The less internal resistance, the higher your potential ROF. Of course, there is a limit. 1AWG wire will be thicker than your gearbox itself. 18AWG is the standard gauge. 14AWG is a fair bit thicker and may have some problems fitting in to some gearboxes. Depending on your pistol grip, you may have some problems snaking thicker wire around your motor. I usually use Prometheus silicone wiring for lowered resistance while maintaining a smaller size. It's an added expense, though. For your setup, unless you're going in no holds barred, you'll be fine with stock wiring.

13) Switch assembly: It's hard to go wrong with that, just get one from a quality brand. KA is okay.

14) If you're going lipo, it's probably a better idea to get a metal body with a shorter buffer tube mount if you want to be able to completely collapse your stock. But that also means you'll have to get a G&P buffer tube to match. They're pretty easy to get.

15) Again, you can't not care for ROF if you want really fast trigger response. If you want really fast trigger response, you're going to have a very high ROF. YOU WILL NEED TO MAKE A COMPROMISE if you choose extreme ends! Otherwise, be like normal people and meet somewhere in the middle. lol

16) If your setup is at 330fps and you WON'T go any higher, then you would be better off with the Tanio Koba Twist barrel. If you go any higher than 330fps, then you'll have to stick with Prometheus. End of story.

17) You don't need high torque motor for your application. A standard Marui EG1000 is fine. If you hate the sewing machine *zip* sound, get good quality helical gears mated to large bearings. The motor won't help you much in that regard. I don't have any experience with Modify gear sets, so I can't say if their high torque models are helical or not.