I ran both the Powerdyne BD-11A and the XB-1 on my old 1995 Mustang GTS. At the time, I too was looking for an upgrade at the least possible cost even though I never had a problem with my BD-11. The XB-1 seemed like the best upgrade since it bolted right into the existing brackets (part of the bracket had to be grinded to fit the oil line).
Unfortunetly, I was never able to see the full potential of the XB-1 since I sold the 95 due to numerous tuning issues. As far as the XB-1 though, it ran awesome. My 95 had your basic h/c/i mods, powerpipe, 7" crank pulley, and the 9lb XB-1. The last dyno I had before I sold the car I saw 12.5psi of boost at 5800rpm (446rwhp/417rwtq SAE). The spark kept blowing out and the car would go no further. I later fixed that issue and the new owner dynoed the car to 470rwhp/420rwtq on box stock GT-40Y heads, Cobra intake, and its not so great tune. He saw 13lbs of boost on an 11lb set-up. From a few others I know with the XB-1, it tends to run most effecient right around 14-15psi. When my 95 worked, above 4000rpm, it was a beast. My Cobra as it sits would still get walked by it (the GTS's lighter weight helps as well). In retrospect, I wish I had kept the 95/XB-1 combo. I have no doubt it would run neck to neck with the likes of the S-trim or P1SC.
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