I run Firad 314's in my 350SD. They've been great so far. They more or less picked up where Bosio left off. Monark are super hard to get anymore and IMHO very overrated (and expensive). If you're going for power upgrades, you want the 314 nozzle over the stock 265 anyway.

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Current stable:
1995 E320 149K (Nancy)
1983 500SL 120K (SLoL)

Black Sheep:
1985 524TD 167K (TotalDumpster™)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)