We have an experience there are a lot of customers who must remake the mufler to fit it in to their airplane.
We can solve this problem!
Muffler with side outlet

Standard dimension: A = 290 mm; B = 290 mm; C = 400 mm; D = 90 °
Muffler with bottom outlet

Standard dimension: A = 290 mm, B = 290 mm, C = 135 °, D = 90 °