I've done a lot of work on all of my pistols and I've used my 1911 as a bit of a teching experiment, trying out everything I could think of to make it perform as well as possible. It's probably not worth it, unless you plan on using your pistol a lot, as it costs a lot for a very small performance increase.
The worthwhile parts are a hop rubber, barrel and h-plate. I prefer ML Autobot rubbers, crazy jet barrels and... well... the H-plate, though I put the ML hop unit and I-key in mine purely because I happened to have one (though the stock unit with the H-plate is just as good in the TM)
As for extra parts, I have the CowCow lightweight blowback unit and the CowCow high flow nozzle in mine, plus the Nineball gas routers in all of my magazines. These all help with the efficiency, but the difference isn't massive. As
@Cr0-Magnonsaid, TM know how to make a pistol and unless you really know what you're doing, you'll just end up making it worse.
I would personally never put a higher recoil spring or a stronger knocker valve (well, one that puts out more gas per shot) in a 1911. Why? 1911s have tiny tiny magazines, so there is only so much gas they can hold. Higher recoil springs need more gas to cycle properly, but the 1911 doesn't have the gas reservoir to make use of it.