I keep reading recommendations about getting specific sized speakers for the particular type of music. All that is BS if your calculations and contruction techniques are correct when building your enclosure.

From what I gather, I would think you are a typical basshead like I once was. Just figure out how much room you want to give up, and what your budget is. That will help dictate what subwoofers you should go with and the quantity. You'd be surprised what a person can do with a pair of VERGE 10" subs

 

The noise you heard was proof that someone screwed up when they were calculating the dimensions of the port/box. bumpin' yota can elaborate more on that if needed, since I'm still Moe Lester's trainee .

The JL amps are nice, but be prepared to be severely disappointed in the JL door speakers.

 

As NisAznMonk said as well as a few others, your box was poorly designed. What tuning was it tuned to? What subs were in it? How much power were they getting? What direction and port area did it have? ALL of those things MUST be taken into consideration when building a box.

A note about those prefabs, be they sealed, ported, 4th or 6th order bandpass:

prefabricated boxes SUCK MONKEY BAWLS!

Why becasue they dont take any of the aforementioned variables into consideration.

Remember that Aura Sound 1808 I mentioned/ Ill put that 18" in a nice self built prosound box (ported of course) and not only will it sound better than 99% of the subs out on the market now, it will cleanly play up to 1800hz and be "tighter" than you can imagine!

If you hear any air turbulence one or both of 2 things are happening. Your port area is too small and thus your port velocity is WAY too high, or you are playing below the tuning frequency of the box. Muddy or boomy bass is usually from a box that is way too big or poorly build.

A good ported box MUST be COMPLETELY airtight and overbuilt as well....