the removal can cause the injection duration to exceed the ability to burn the fuel dramatically increasing egt without any appreciable power gain. i would recommend around 2-3.5 turns in on the limiter max after that it wont help your power any just make for hotter egt's. all this is assuming you have a turbo or some other way of getting more air into the engine since 616's are basically maxed out stock as far as ability to burn more fuel. the 5.5mm elements are not good for any real power when i went to the 8mm M pump on my 617 it gained quite a lot even off boost from the shortened injection duration and timing.

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1985 300D om617: 8mm M pump 175cc 5200rpm, holset he221w @ 30psi, large A2W ic, compounds on the way.
KD9AFT
A&P