Looking for a great solution for a brake booster for your E30 M/S5x swap? This is a great option! After completing several swaps at our shop, we have found this booster setup to be the best performing and cleanest solution for your M/S5x swap. This is a plug-in swap just requiring the parts from your stock booster responsible for the mechanical connection to the brake pedal. 
 
With a significantly smaller booster diameter, this eliminates the issue where the intake manifold interferes with the stock brake booster when completing the M/S5x swap. Expect a slightly firmer pedal feel than stock boosters using this booster. 
 
This is a new ATE booster which we then modify at our shop so that it will plug and play into M/S5x swap cars.