Will I see a big difference if i update from an aq3500d (old one 3500 watts) to a saz-4500? I am looking to get my 2 dd3512e louder. Would this get me there?

Yes.

more power = more db's i don't see why not

but for the db's to be noticeable you would need double the cone or double the power. some ppl say if you double the power and or double the cone you can theoretically get 3db's with either upgrade but practically you will see 1-2db's with either upgrade.

so lets look at your situation to get 3db increase you would need 7krms so to get a to get 1.5db you would need 5250rms and around 4500 would net you around 0.5 db's

it is only 1krms more. it isn't a huge increase.

but then again if you cars electrical sucks an amp upgrade will not do to much.

so let see tell us some info about your box, your car, your electrical and your experience with db hunting and some of the guys on here will make some recommendations on what you can do to gain some db's also how much sound deadener do you have in your?

Make sure you have the electrical!

My box was made a little smaller than it should be at 2.25 cu ft per sub due to that my trunk is not that big (honda accord) and tuned to 34 hz.. I have this set up running on a 180 amp alternator with 2 kimetik 2400 and 1 kinetik 1400 in the back. I am looking to upgade my alternator to 300 amps in the near future. I have an aq2200d laying around so i thought about getting another one and running two of them strapped. What other amps should I be looking for?

What are your goals? SPL competition? Or an absurdly loud system for driving around in?

A loud system for now and if I happy with the numbers then maybe spl competition.

Then I would say the Sundown would be the way to go! But I am partial to Sundown ....

10*log(4500/3500) = 1.1db

That's the maximum theoretical difference. Realistically that doesn't account for factors such as power compression, the ability of your electrical system, etc. Just factoring in power compression you are going to be looking at an increase of somewhere less than 1db.

Audible difference? Nada.

Difference on a meter? Probably, but only worth it if you are trying to chase down every last .1db

If this is for a road warrior system with minimal competition time, probably not worth it. If louder to your ear is the goal, this upgrade likely won't get you there. Increasing power to increase output is the least efficient and least effective (and normally most expensive) method of accomplishing that goal. If you want to increase output, look at improving your enclosure first and foremost. It's the easiest, cheapest and most effective method.

so lets look at your situation to get 3db increase you would need 7krms so to get a to get 1.5db you would need 5250rms and around 4500 would net you around 0.5 db's

The relationship is logarithmic not linear, but other than that I agree with your premise. Not enough of a difference to be audible.

10*log(Power1/Power2) = decibels

I c I haven't come acros that formula before thanks for it I will use it more often

I c I haven't come acros that formula before thanks for it I will use it more often