Black129. I would never run less than 91 in any gas powered mercedes. If you want your car to be quick try the Nitrous kit by Bergwerks, current application is the 500E, which is the same engine you have.

The factory box location with K&N filters is far better than a cone filter in the engine compartment. K&Ns help maybe a little, but they catch a lot more particles and they are farily easy to clean.

One of my friends had a cone filter behind the front bumper like how 2phast did it on his old C36, and she hydrolocked her motor, if that was a benz motor that would be $$$$.

Hot air intakes are a different story.

__________________
Current Stable:
1994 S500 v140, 210k miles, white with grey.

Former Mercedes in the Stable:
1983 300CD Turbo diesel 515k mi sold (rumor has it, that it has 750k miles on it now)
1984 300CD Turbo Diesel 150 k mi sold
1982 300D Turbo Diesel 225 sold
1987 300D Turbo Diesel 255k mi sold
1988 300 CE AMG Hammer 15k mi sold
1986 "300E" Amg Hammer 88k mi sold (it was really a 200, not even an E (124.020)
1992 500E 156k mi sold
etc.