Anybody have experience with upgrading thier 575SCI's using smaller pully's that raise boost to 7lbs from the stock 5lbs? How does 91 octane pump gas work, and also how about 89 Octane
as some on the water stations only supply 87. Did you have the
ECU's reprogrammed as well?

Do a search on this question, there was a post on this not too long ago.

friend did this.

BUT

also added intercoolers and upped fuel pressure a tad. No ECU mods.

Super chillers, pulleys, and pressure regulators.

Mucho improvement.