240SX rear brakes

Hi,

Is anyone a 240 SX rear brake caliper expert? Here's the deal. I am building a new race car and I am using this caliper. I am not using a handbrake and got rid of all the related parts. Aftern a couple hours trying to find out where this system was leaking I had the entire assembly submerged in water and was shooting air through it. Lo and behold, there is a factory pinhole in the grove of the piston!! Yes, the only thing to cover this hole from all the pressurized fluid is the flimsy dust boot that rides in that groove.

Is anyone familiar with this and is this right?

Thank you,

Greg