So when i turn it up...
 

Okay so ive this system i build for a while and ive built many systems and never had this problem but when i start pushing the system it actually bogs the motor and my battery gauge doesnt move and my lights arent dimming at all .. Usually on certain songs i would get a little dimming here and there but when i replace my battery with a big optima it eliminated that.. Every says alternator and ive thought that too but i dont understand how it could be that if my dash lights and my gauge doesnt move if its lacking power wouldnt all my lights be affected before the motor actually hesitates ??? Maybe im crazy and its nothing with the stereo at all but it only does it when i start turning it way up and not always will it do it.

My system
infinity 4 channel 650watt
2 full sets kappa components(so 4 mids and 4 tweets)
2 mtx 10inch subs cheap not high end
mtx 750watt mono amp

When the truck is running, it's running of the alternator, not your battery.

I would have it tested

If it "bogs" the motor like turning on the A/C does then its the alternator.

Alternators pull horse power just like A/C compressor does, no mystery in that, the more electrical power(amps) you pull the more horse power you use.
I doubt a bigger alternator would help, amps are amps, if your lights were dimming then I would say get a bigger alternator.
But in this case you would need to get a bigger engine to turn the alternator, lol, because it is a horse power issue.

A better word would be bucking I guess it's like it starts cutting out but it won't do it unless the stereo is way up ill try and take a video of the tac so you can see what it does

Alternator. My mother in laws car had a similar issue. It isn't the extra load on the belt and pulleys. Your stereo is taking power away from the ECM. On hers, when you turned the a/c or stereo on you would get a dead pedal. Hit the gas and nothing happens at all. The ECM can't function properly without enough power and some functions start to go. I her case the accelerator pedal. In your case it sounds like the the injectors.

Wait, first things first. Get a multimeter on that puppy and see what the actual voltage is when you get the ''bucking.'' And second, the ecm will operate down to around 10.5v iirc so if this is an issue that happens at idle, it might just be an Iac issue. With my headlights on and heater full blast, i can get my system to drop the voltage to around 13.5ish at idle and i swapped in a larger expo alt and i dont have a bogging issue.

I have a 3.0 and the alt has never made it bog, even using my 8k lb winch. So i highly doubt its a hp issue with a 4.0

Now i have noticed a 50-100 rpm dip when the bass hits but thats to be expected, it is being loaded down more just like when the a/c compressor engages. If the rpms are bouncing around i'd bet you need a new Iac like i mentioned earlier.

I can't put a multimeter on when I'm driving ..

You would do the test idling, but you can hook a volt meter up to any inside 12v source and a ground to watch it while you drive

ill have to try once the weather gets better its been really stormy the whole week

install a capacitor it will soak up the parts that are bogging down your engine. im not sure of the size you need though

It was the cam sensor causing the problem not anything with anything else