Multi spec is best shot with low air if you want large vibrant colors especially the stone accent line.
The heavy bodied material is also e easier to work with if you add 15 to 20 % water. I prefer distilled water as it slicks the fleck up. I supply hundreds of companies and I'm in the industrial spray equipment business. We are ac warranty equipment repair center for just about anything that sprays.
We have servicing the refinishing market for 30 years and this is a question I get daily.
Multispec can actually be sprayed with a 1.3 but 2.0 to 2.5 with 20 % water with the fluid set 3/4 open at 10 psi and back will produce large vibrant colored flecks. If you spray above 45 PSI the Fleck will be destroyed and it will dry down to a dull gray haze. I normally suggest those gun settings only just before I spray I shut air completely off, point the gun at a test area pull the trigger back, then slowly rotate the air control valve up, the gun will begin to spatter but slowly increase the air until the gun begins spraying a nice even steady pattern. This will allow you to achieve the largest fleck with vibrant colors. Cross hatch spray so the fleck does not look wind blown in one direction. Even using a 1.3 mm tip using this method you can still get a nice pattern. The higher the air the smaller the fleck. Gun setting are actually more important than tip size. The fleck go down wet with a blue gray haze. That is the preservative and it will fade too the correct color. Prior to loading your cup use a wisp normally used for eggs our batter to slowly break fleck up so it does not clog gun. If you apply a non water base primer down first, be sure to Flush gun then run water to make your equipment compatible. If you don't the solvent with turn the fleck to gel.
My name is Gary Goel and I own <a rel="nofollow" "//www.refinishersonline.com/" target=_blank">www.refinishersonline.com</a>, E.A.H. Industrial Spray Equipment & Coatings. Thanks for reading. If you post your project I'll be happy to spec it out for you based on durability requirements.