Is there any easy ways to tweak a 1982 380SEL engine for more response and horsepower?

Thanks in Advance.

Bart

My 10 cents:

Tubular headers and low restriction exhaust system (kinda expensive).
Tuned headwork (flow coefficients upped about a point int/ex). Stock valves and even stock port sizes should be fine, I'm just talking about a good hand finishing. And port match the intake manifold runners.
Free flowing air cleaner setup, something like a K&N in a cold air box.
Block off exhaust reburning if your finished product will comply with local emissions regulations (keep manifold heating though if it has it).
Computer modelled *mild* camshaft grinds. These can help with emissions regulation compliance if done properly. Off the shelf grinds offered by AMG or similar would have both dimensions I just mentioned there, but I like custom grinds myself.
Upgrade injectors to 20lbs/hr.

I'm still working on getting all the M116/117 details into my Engine Analyzer Pro so I couldn't tell you authoritive projections on hp increase, but these kinds of modifications should certainly change the characteristics of the 3.8 to one both far more responsive and more powerful. Fuel economy would respond to how you treat the accelerator pedal in traffic (volumetric efficiency is up by 5-10%), reliability would not be adversly affected at all.
Idle shouldn't be overly put out, maybe a bit sharper but certainly not enough to worry about other drivetrain components.

Actually if you're interested, bart I have to do some computer modelling for my brother in law's 1984 380SEL anyway, for pretty much the same thing you're after. I'll be picking up a cd of technical data from my other brother in law's place sometime soon, but if you've got some details on the stock M116 handy, feel free to post them and I'll get back to you with the results from my Engine Analyzer models, down to some mild cam grind specs and their projected effects if you want.

what I need are valve diameters int./ex.
port dimensions (including length to chamber if possible)
intake runner length and inside diameter
throttle body diameter
stock cam grinds

the handful of other figures I can adapt from a M117 base and adjust until I get stock outputs, double checking when I get the tech data. It worked out to be a pretty reliable system for the M110's I've been modelling for second brother in law's W123 (although port lengths and flow coefficients could be a little out...until the next time he pulls the head down and I can start shoving guages and calipers in there).

There's just no detailed engineering info about 70's-80's Merc engines on the web, ya know?