KU40

Either are good if built properly.

Well then I wouldn't put anything in the dash. Just get one good set of components for the doors.

You're probably driving the sub into distortion. Turn it down before you blow it.

That's why the amp is so cheap. Not reliable. However, just to be sure, you should check the resistance of the sub's coils with a DMM to make sure they're ok. Also make sure all connections are secure and stray wires aren't arcing across the sub terminals, box terminals, or amp terminals.

Yeah, I was thinking that also. You may have fried it with undervoltage. Amplifiers aren't the only casualties of war when voltage dips too low in the car.

There's a bit of a range of where increasing port area can be helpful and a point of diminishing returns. For example, with an average 12" sub, 5 sq. inches of port area would act more like just a leaky hole in the box and not like a port at all, and you wouldn't see the beneficial gains of having a port. 20-50 sq. inches may be acceptable, and 50 sq. inches may be like .2 db louder than 20. But then as you keep increasing port size, diminishing returns sets in and you can even reach a point where too much port area is detrimental. If you try and put like 500 sq. inches of port area on one 12" sub, it's not going to act like a port at all either, and more like just a giant leaky box or even just free air, since there won't be enough back pressure through the port to help the suspension of the sub keep it in line. So you do need some resistance through the port, but not too much.

Could be. Did you ever hook it up at 1/2 ohm like you were thinking about trying in your other thread?

Can you mount 6.5s in the doors?

There's nothing really wrong with them, but they're just a capacitor. It will give you a -6db slope at the frequency. Don't buy those "name brand" bass blockers. Way overpriced. Just go to partsexpress and buy a large capacitor the size you want for the frequency you want at the impedance of your speakers. If it were me, I'd get an amp for them and use the highpass feature on the amp. However, I understand price constraints. I'd say something like 100 hz for the 6.5s and 6x9s is fine, and 150 hz for the 4s is fine.

There were plenty of good things being said about those Oz Audio MEs a few years back. I've never heard one, but if the sub is in good shape I'd think 120 is a good price. I think they may have went for 250-300 new?

Will the 50-75 percent reduction in port area result in a decrease in output? No it will not, do to the smaller enclosure size That has nothing to do with it. No, the decreased port area won't have any affect on output so long as the area is still sufficient to keep the air velocity through the port down. That's really how more port area (such as in a slot port) helps you, by decreasing air velocity through the port. So if your port velocity is 13 m/s with a 100 sq. inch slot port and 13 m/s with 60 sq. inches of aero port, there should be no difference.

You're running their SQ sub in a sealed enclosure. So that score is decent enough, and if you picked that equipment for its capabilities you shouldn't really be worried about dbs.

never knew that... Mind explaining why/ how it lowers fuel economy? More drag. Sure the car is the same size, but when you raise it up more air goes under the car and hits everything down there, like axles, exhaust, control arms, etc. When the vehicle is lower, most of the air is pushed out to the sides and skirts around the outside of the car instead of going under it. I've heard of people putting a spoiler under the front of their truck that nearly touches the ground and it improved fuel economy. I'm sure it looked weird though. And I'm not sure how much it would affect it on your car, it's impossible to say. May not be noticeable. Hmm.. pretty much the same as having the windows open vs using the ac on the highway i suppose? I suppose. If I remember my Mythbusters right, they said something like below 45 mph windows down is better, above 55 AC is better.

If you have a 4" aeroport, the area is the area of a 4" circle. If it's a 6" port, the area is that of a 6" circle. The flares on the end don't count for port area. However, you actually did write a correct question, and that is the "effective" port area of an aeroport. Not the actual port area, which some of these other guys apparently thought you asked. Generally, you only need 50-75% of the port area when using aeroports. So if a box and sub would need 100 sq. inches if using a slot port, you should be able to get away with 50-75 sq. inches with aeroports. That helps keep port length, and thus port volume, down so that you don't need as large of an enclosure in net size. But also, they don't "trick" the sub into thinking anything, they just allow for smoother airflow in and out of the port, which reduces the chance for port noise. Port noise is one of the main reasons subs need the port area that they do.

It's not risky at all to run one amp on each voice coil.

never knew that... Mind explaining why/ how it lowers fuel economy? More drag. Sure the car is the same size, but when you raise it up more air goes under the car and hits everything down there, like axles, exhaust, control arms, etc. When the vehicle is lower, most of the air is pushed out to the sides and skirts around the outside of the car instead of going under it. I've heard of people putting a spoiler under the front of their truck that nearly touches the ground and it improved fuel economy. I'm sure it looked weird though. And I'm not sure how much it would affect it on your car, it's impossible to say. May not be noticeable.

Why are you condoning drinking and driving? Raising the car will lower fuel economy. But I guess you have to balance that with comfort. Not sure how it rides now.

How are they going to be rated on stock electricals when every stock system is different? Your car has an 80 amp alt, mine has a 130. How do you think that changes things? And to get 4000 watts from that amp you'll need about 450 amps of current. How is your 80 amp alt going to do that? Being "power hungry" is a relative term that is thrown out the window when you're talking about 4000 watts. What's the difference at that level if the amp is 80% efficient and pulls 450 amps or 90% efficient and pulls 420 amps? You're still pulling 400+ amps. Not gonna matter.

I would absolutely buy a larger alternator if you want to get even 1/2 the power out of that amp (that the sub is rated for)

If you need to refurbish it, I believe he will send you to db-r.

All he's going to find is 1/0 gauge. I've never seen 1 gauge. Anyway, to the OP, 0 gauge IS 1/0. The 1 just means one zero. To take it further, 2/0 is written out as 00. 3/0 is 000, 4/0 is 0000, etc. The more 0s, the bigger the wire. Find some 1/0, buy it, and find an ANL fuse holder and buy it (I assume the 90 amp fuse you have now is an AGU fuse?), and buy a 200-250 amp fuse for the fuse holder. That's all you need. It's not hard. You do need the 1/0. However, you don't NEED the bigger fuse if this one never blows. You could put the AGU fuse you have on the 1/0, and if it ever blows, then replace it with an ANL. It may never blow. I have a 100 amp fuse ANL fuse on my 1/0 wire with a 1200 watt sub amp and 200 watt 4 channel amp, and it hasn't blown in the 5 years I've had it.

You shouldn't run any amp at low voltages. If you have a problem with that, fix it.

Nope

250 amp should be fine.

Fuses don't bottleneck power. Just because it's a 90 amp fuse doesn't mean it will only allow 90 amps to flow through it. They don't restrict power. They only react to power flowing through them. Fuses won't even blow if you have more than their rated power flow through them for a short period, as transients in a song call for. It has to be a sustained draw for up to a couple seconds. There is an SPL competition organization that makes classes based on fuse size, and you know people put as small of a fuse as they can on as big of an amp as they can and really test the limits of the fuse, but they only need that one second burp so the fuse doesn't often blow.