Zahanma beat me to it...
I would not go without the inner cooler when running a 185mm.
Depending on where you are buying the 185mm, I am pretty sure Eurocharge is still offering a Pulley & Tune special.
I KNOW FOR A FACT you will be disappointed if you just put in the 185mm pulley until you get it tuned.
Now a pulley, cooler, intake and a tune and you can forget about ever mentioning that big "8" boat on this forum again!
good luck,
Mike