[///Mark_D]

The autobox does sap some power, so swapping to a manual transmission will definitely liven it up a bit. Especially if you also swap to a 3.46 rear end. Check out this online calculator that shows what gear ratios and rear ends were standard for each model type.

BMW E46 Gear Ratio / Cruising RPM calculator

Both the auto an manual trans cars still feel slow-ish by modern standards, but the manual cars are much more fun in my opinion. I've got an automatic 325xi wagon with a 3.0L engine swap, and it feels just about as fast 0-60 as my 325i sedan with a manual transmission. I've also got a 325i wagon (which came with a 3.46 rear end vs. the 3.15 in the sedan) and that car feels the quickest of the three in terms of off-the-line acceleration. The 330xi swapped auto wagon has more pull at highway speeds.

Manual swap DIY's are pretty well documented here and on Youtube, so you should be able to put together a list of parts you'll need from a donor car. Having a lift would make the job easier, but you can do it on jack stands in your garage. If you're looking to up your enjoyment of the car I'd say go for it.