Positive they are 25mm Eibach Pro-Spacer Hubcentric Mustang Wheel Spacers - 25mm - Pair 90.4.25.010.3 (94-14 All) - Free Shipping
Not sure how much clearance you need but you need at least 1/2 an inch to clear the brembos. there is one guy who reviewed these that is doing the same thing as me, using the stock 18x8 rim with the 4 piston brembos.
2014 Mustang GT 6R80, Procharger Stage 2 D1SC, BBK 85mm TB, Boss IM, Sai Li fuel system. Circle D 3C, 1-7/8" Kooks Long Tubes w/Offroad X Pipe, Lethal Over-Axle Pipes, Corsa Quad Axle-Back, Eibach Pro System Plus, BMR K member, Shaftmasters DS, Forgestar CF-5 Wheels and Nitto NT05 tires. Lund Tuned
Lots of suspension goodies and some other stuff I can't remember.