Is there any way to increase the power of my 1990 300SL in the way of bolt-ons or tuning adjustments?

How fast do you want to go? = How much do you want to spend?

To get gains you can feel you would probably want either a displacement increase from a tuner or a twin-turbo kit. The tuner thing will cost big cash, the twin turbo kit will give you about 300HP for approx $7500 bucks. Of course you could run a small (low HP) nitrous kit for occasional bursts of power for about $850-$1500. There was also a manual trasmission option on the early 300SL's but I'm not sure exactly what all would be involved in the swap. (assuming yours is an automatic)

If those options are all too extreme for you, exhaust and some intake tweaking might get you 10-15 HP at most. If memory serves your 90' model year engine/electronics were not readily "chipable". Benzmac and myself are looking into how we might change the "chipable" status of the CIS-E management. If/when we find something solid would you be interested? IMHO computer tuning is the most cost effective performance you can get on a MB except perhaps stickier tires on high-torque cars. Speaking of high torque cars, you could just trade your 300SL for a 500SL. I'm not trying to put down the 300 it is just Mercedes can tune a car alot more completely than any of us. Also before you go wild with upgrades find out what it would take to trade out. Not to mention the damage to resale value that any mods would make. Then again, I am selling my 400E and picking up a 500E so I have a bit of experience with that. Just a thought...

If you have any more questions or are interested in any of the things mentioned above feel free to post back or email me.

Happy Motoring...Lee