I have a pair of 500efi's that have upgrades done to them. They will be in a 2000 38 Lightning. They are making 580Hp and 600ftlbs of torque. I have to buy drive couplers because they did not have them. I have purchased the Sierra version or the Mercury coupler. I have been told it is not as good and I need to get the mercury ones. What do you guys think?

I would seriously consider using Drive Guardians instead of standard couplers.

Padraig

Im running the stock Mercury bravo style one's and my 540's are making 630hp, so I don't see an issue

you will be fine,,if you set the merc ones next to the sierra ones you will find that they both have the same markings on them which tells me they come from the same mfr..

Ayuh,.... I've also found that to be true,....

Model for model, I haven't had any problems with the Sierra's,...

The sierra is the same for sure and my buddy is running one with a 900 hp procharged 516 in his 25 baja. No issues.

Great!!! Thanks for the help. I've got a pair on order.