Originally Posted by biopete

Not much. I installed 4 new turbo nozzles in a 240D with new nozzles. It had 115 bar injectors but when done, pop pressure was 150 bar. Runs good. It just makes the ip work a little harder to get higher pressure but they can take it ( i would assume). Gives you better atomization of fuel. You get a little more nailing but new nozzles do that at first anyway. Also it may retard timing slightly so you could check timing and advance a little if need be.

BTW, can you advance timing by sound on these engines when running it -- ie loosen IP and just push a little toward engine and tighten till it sounds and feels good?