The factory merc curves are rich!!!!!!! Think of it this way, if merc put a lean fuel curve out there, and a lot of people were burning pistons. How many would they sell????.
Brucato is the same way. Safe is a great thing for them.
The horn curve is a leaner curve, the horn air volume is less than a svs.
Less air means you need less fuel. If you run a horn curve on a svs you going to have a leaner curve. I haven't done this, I have a custom curve in mine.
The svs curve drinks the fuel in the mid range...
Gohr will set you up with a better curve, but not to lean I'm sure..
He can explain his curve/map to you. He know all about the svs.
JMO
Roy