No, the two items are unrelated. You don't need a boost gauge on a stock car. You can fit one if you like. You don't need a manual boost controller on a stock car, and usually you don't need one on a correctly modified car until you reach some point that is beyond the "if you have to ask" stage.Do yo need a manual boost controller in order to have a boost gauge??
+1 if I would have had a boost gauge when I moved to Florida two years ago I would have realized I was running about 22 psi at sea level instead of 15psi when I was in Colorado it took exactly one day in Florida for my turbo to go boom.The MBC replaces your OE solenoid on the passenger strut tower. A boost gauge gets tapped into the vacuum line off the OE bypass valve.
As Spiros alluded to, they are unrelated. While a boost gauge isn't necessary on your car, I find it a useful gauge to have, and it would be worth your purchase.