The sub is 32cm wide. I thought I gave him a 38x38cm front plate. Colleague Bonnis gave me the tip, leave behind the magnet approx. 7cm space, must also be ventilated the thing. mdf is 2,22, sub approx. 16cm deep. So now quickly calculated 38x38x(sub-deep MDF thickness+7cm) are therefore 38x38x20,78cm and you get just under 30 liters. Would still fit if you assumed that woofervol. would be 2,5. That would be added to the 26.9 and you would have 29,4 Li ter. So now the thing would not have been adapted to the back bench. I would then be 38 liters, with my measurement of the back bench tilting angle having resulted in 68.6 degrees. My solution would be to build a housing that has a parallelogram as a side surface, then the woofer would be pointing down and it wouldn’t be easy to build either. So what do I do now?`