Potter did that with mine along with a few other tweaks and we are now at 700!

Pretty happy with my 575scis after my 700hp mods, however if you are going to invest into these engines there are lots of little things you should read up on, just like stated above.

The stock flat tappet drive train is dated, and chokes the engine IMO. Roller conversion really wakes them up
The early wieand blowers have a dual bath and are said to be stronger, they however still need some updates/upgrades.
The later bm blowers do not have an oil bath in the rear and need sealed bearing retainer updates
The stock tune is prob the worst tune merc ever relased. Pig rich, so much that oil dilution and piston wash can be a real problem in colder climates.
If it was ever ran in salt take a good look at the thermo housing, chances are it is shot and will cost you over $1000 to replace....if you can find one. Same for the intake that is not brass lined.
Stock pistons are no longer available
Valve springs should be changed at 200-250
HG...see above
Lower end is stout, many have H beam rods.....but not all, go figure.

My set up

Full roller, aggressive cam
-2 mechanical timing
120 degree stats
Custom tune with cold start delete. 11 AFR WOT, 12.5 no boost (safe ish)
3 1/2 and 3 1/4 pulleys (thanks biggus)
MLS HG
Head studs (why not)
blower updates from DMPE
I run mine between 5700-5800 RPM WOT depending on air conditions. It will hit the rev limit at 5850 in the cool air.

Night and day difference after mods. I wouldn't shy away from a 575sci, however it may be classified as a hobbyist engine as they continue to get older and more finiky The gen 7 600sci and 700 sci are worlds ahead in advancements, and parts are much more common.

The 871 blower upgrade is a hot set up.

What heads are on the 575sci?

I have a 2005 with 575's

A couple of notes.
4 BUS hit it on the head
The older style Weiand Blowers are much better than the newer B&M that they used. (goes beyond the oil bath)
I actually get better fuel economy with the upgrades even with the HP increase.
Supposedly the Blower Shop is or will be making a custom intake manifold. As stated, they do go bad in salt water and are getting EXTREMELY hard to find.

[ATTACH=CONFIG]539433[/ATTACH]

After I learned the hard way and fuked mine up - Smith punched out to 509 full roller, Alum heads, whole new fuel system to feed them, and a few other mods- pumping almost 750 now.

Oh and Don't forget Eddie Young tune! That was the ticket to Smooooothness!

And of course the SCXs to handle all the power

Run of the mill GM iron rectangle ports with inconel valves and crane gold rockers.

I have a bunch of stock pistons left over after going to 509 if anyone is interested. Heads on mine are 934s and I think mine are 2002 with weiand blowers. basically did the same mods as 4bus and biggus, but no chillers.

509
Fully Balanced and blueprinted bottom end
flat top JE pistons upped compression to 8.23
Felpro MLS gaskets and ARP head studs
Heads cleaned up and unshrouded
All new valves and ISKY springs
525EFI cams
Morel roller lifters
Crane gold roller rockers
Blower gone through, stripped, and freshened by Mooneyham
120 degree thermostats
3.5" pulleys
Throttle bodies rebuilt and injectors flowed
Custom tune from GT performance

Hope to have engines installed and boat on the water by Memorial Day!!

Who did your injectors? I really need to send mine out this spring

And I have a friend that melted down a piston last year, his engine is apart now and I gave him your user name.