Been looking to do a 4th order for a while now. I have contacted several people, got mixed answers. I have two 10" hdc3 10's that I want to use. Some people say they shouldn't be used, but the guys from audioque say people have a great deal of success with them. So I am looking to make one and have it ported into the cabin through the rear deck. I have some cash in paypal for a design. I just need a pro to work one for me. I know 80 inches is a guru on this stuff so maybe he can chime in. I am fully capable of building the box myself, just need the plans. Pm me for details and dimensions if you are interested. Thanks guys.