Is it possible, by adding resistors or re-wiring cabs to make a 4ohm cab, an 8 ohm cab? I thought that perhaps putting a 4ohm resistor (i dont even know if these are available) in series with the 4ohm cab that i would gain an impendence of 8 ohms, or how about we wiring a 4x10? i know you can dercrease the resistance this way and i doubt you can increase it but hey just brainstorming here
If you add another 8 ohm (resistor in parallel to the box), you'll just turn 1/2 of the power into heat (lots of it, these need to be special resistors with passive coolers), it won't get any louder. That's why guitarists use load boxes to get their poweramps into saturation without getting too loud. Since you want more volume as a result, you need a transformer. Glockenklang used to offer one. But for that price you can get a used 2x10. Add that and you have your 4 ohm, more speaker surface too.
Of course a resistor can be added in series to increase from 4 ohms to 8 ohms. It would have to be one heck of a big resistor to dissipate the heat...But other than creating a very nice heater inside your cabinet to warm you on those cold winter nights, you wouldn't see any benefit at all. Lots of disadvantages, including putting half your amp's output power into heat, and reducing your amp's damping factor. (Yes 4 ohm resistors are readily available, to handle anything more than a few watts requires wire-wound power resistors, preferably fan-cooled) As far as rewiring a 4x10, if it was a 4 ohm cab to start with, the only other practical combination would be a 16 ohm final load. (You can rewire it into an unbalanced configuration but that's not good) Sorry, but you're stuck with a 4 ohm cab. Buy another cab or change the drivers.
The only other way it might be helpful is if for some reason your amp could deliver more power into two 8 ohm loads than into one 4 ohm load. In this case, it might make sense to wire each pair in series, with the amp seeing two 8 ohm loads, one per channel. But yes, for all other circumstances what everyone else said is correct.