[BruceJ]

Wouldn't change much with the exception of:
1 The plastic charge pipe
2. Fix a couple classic BMW plastic cooling system hoses, one found directly over the radiator, under the kidney air intakes. Its a hard plastic 1/4" ID hose attached to flex hose on either side. After a few years of heat/pressure cycles, it snaps if you just touch it. Either replace it preventively at about 30k miles (its pretty easy to get to) OR, replace the plastic pipe using barb connectors and a flex hose, or SS; just about anything is better than what they used.

The other is found directly attached to the block on the passenger side. probably under the thermostat. Its a flexible modern hose, but..... wait for it BMW terminated the side of the hose that goes into the BLOCK with a o-ringed hard plastic that has a flange that is bolted to the block in two places. Besides the fact that its hard plastic, you would think that if you connect it like that the bolts would be 180 degrees apart. but no, they are about 110 degrees apart, which means the flange is more at risk of breakage because of how easily torque is applied to it. It gets broken commonly when the thermostat and/or water pump, or turbos are replaced. The fix for this is either replace the whole hose or replace the flange with an aluminum one off ebay. This hose is not so much fun to get to. But if you just opt to replace it as an OEM its not that expensive.

Running just JB4 on the 335is with DCT does not seem have gone well for the few folks that posted with this combo. The DCT shift points are not included in the JB4 and this seems to be the crux of the issue. May have been fixed by now with a MHD backend flash, you'll have to see for yourself.
Otherwise, IMHO of course, the engine, intake, exhaust are pretty much a holistic synergy, if you are going to do something to one you really don't see much benefit without addressing all. And once you do that darn DCT has to be addressed or it just doesn't seem to work out. Then, if you do these things, EXPECT to buy new plugs, coils, injectors, fuel pumps(high and low). No whining that they prematurely wore out cause they will.

But rock on, maybe you and others will crack the high HP/DCT code and when I see enough happy folks with still working engines/DCT's I might jump in.

Good Luck
Bruce