Originally Posted by sonoronos
How do they handle oil return flow from the turbo?
FMU would work, but it's definitely not for high boost.
Piggyback ECUs would work for this application also.
Oil return feed is handled via an electric oil pump. Its a heavy duty pump used on big diesel rigs special order for ~$150 if I remember right, they are pretty long lasting and it has had pretty good results.
I've seen FMU's successfully used on boost applications up to 15psi without any problems. The trick is picking the right ratio FMU. FMU's are safe and easy to set up but don't get you max hp as a PCM fuel trim map would - most Vortech FMU's, for example, are set up to run a bit on the rich side. However If I ever ventured this way I'd probably get an adjustable FMU and a wideband which I think would do the trick....
3.8v6 camaro guys with stock 2.25 piping have had success with running t3/t4 hybrids (with redone exhaust piping of course). And that's a pushrod 1intake/1exhaust valve engine. I'm not familiar with the cam profile of the 3.2 benz engine engine but turbo surge is usually not a problem if you know what you're doing when picking out the right turbo for the job.