I want to extend my guitars upper range then the lower range, the highest note is a B6, high e. I want to have my highest note being in the B8 range if possible. but open string wise, i would rather have 2 higher strings then 2 lower ones. How can this be achieved?
Given that it's a normal 25" ish scale guitar, and you want to get a top string up to three and a half octaves above a normal top string, it's hardly going to happen. Imagine going up one octave. The standard string, say .010", will have to be approximately twice as tight. Two octaves, way tighter still. Or, for about the same tension, one octave higher, half as thick. So without going into detailed maths, for what you are hoping, it's a string about .003" - much finer than human hair, and under far more tension than the other strings. Quite well on the road to breakage!
The other option is to shorten the string/s somewhat like a banjo, which requires major surgery on your neck.
First off, on an E standard tuned guitar (ie, a high E4 string), with 24 frets, the highest fret-able note is an E6. Remember that the notation for guitar is written an octave higher than it sounds. For playing higher than that there are a few options.
Higher tuned strings. Up tuning very thin, plain steel strings is the most obvious option, but also difficult. You have to take into account the scale length as well, and this will work much better with a shorter scale length like 24.75". According to string gauge calculators you can get a 'G4' with a .009" string at 17 lbs of tension alright, and even a 'G#4' with a .008". Getting an 'A4' is much harder but would be doable if you don't mind playing really soft so as not to break it since you might need a .007". A 25.5" would have a much harder time with this, and any more tension has the tendency to break strings at such low gauges.
Multi scale length. When manufacturers started making 8 string guitars some of them realized that having the same scale length for all 8 strings was a huge compromise, so they looked into making them all different. Fanned fret designs started to gain popularity as did headless designs, so now we have brands like Strandberg that make a living off of selling these style of guitars. Getting a custom made guitar with a short scale length for the high strings would be the best way to up-tune. Something like a 23" scale length could tune to A4 with a .009" or .010" with 20 lbs. of tension easily, allowing you to use regular string gauges. If you use thin gauges you could potentially tune up to B4 for a high note of B6. Unfortunately, this short scale would be rather awkward to play if you wanted a normal, 25.5" scale length for your low strings. The fanning of the frets would be quite extreme, and the custom order would surely be expensive.
Short scale length. Buy or custom order a guitar with an overall shorter scale length. This will most likely severely effect the tone of the low strings and may even require ditching them, but it may be cheaper than a multi scale instrument. Another option would be to ditch guitar altogether and play the mandolin.
Play with more harmonics. This is what most guitarists do, and I especially notice it in metal. Pinch/artificial harmonics are the best way to play extremely high with a standard tuning, and with distortion they lose little energy or tone. Using thicker strings can make it easier to get strong harmonics out of them.