I have a good sized cab i pretty much built. It is lined with fiber glass insulation on the inner sides and back. It also has 4 - 6x1" vents, 2 on top, 2 on bottom, and 2 8x3" vents on the left & right of the front panel, between each speaker. 2 - Eminance delta 15's Wired as 4 ohm's (should handle over 600watts) When i crank that bad boy up to 450 watts. It sounds all distorted like the cab is ready to blow apart. Should i put some air relief ports in the BACK where each speaker pumps the most, Or is it bad to have ports front AND back?