Hello, I have converted my 560SL to manual 4 speed trans. And i am now looking to get more power out of the 117 560 motor.

I'm looking for any suggestions does anyone have any experience in performance tuning on these engines?

A couple options ive looked at are tri Y headers but they are hard to find.
A 560 sedan engine transplant ive heard they are more powerful but im not exatly sure how much as some list to be as much as 295hp. but is that euro or ECE only? and what is the difference between that engine and my current SL engine? as the stock SL engine seems to have the least power of the 560 range. I know 10:1 compression might be one thing but is that just in the gaskets?

Another thing ive heard about is EFI conversions, I have a full EFI system from a 450SE if that is of any use...? Also ive heard of converting a 500 engine to 560 by using the rods in the 500 engine I have a 500 euro engine does anyone know the specific specs of that? or what i could make out of all of this to get more performance?

Lastly ive been messing with the fuel tuning if i richen it i get noticebly more power revs up better but doesnt idle well. if i lean it it idles fine but noticibly less power and punch in first gear. could i adjust the timing or anything to smoothen the idle when running richer?

any help would be apreciated.

thanks