As a mechanic I can tell you if you bypass that voltage and unregulate it, reason for a regulator, your also gonna up the amps as well. A little now is fine till something goes wrong and you fry important components such as an ECM wich cost well over 700 to fix!
If your looking for that extra punch in the stereo, get a second battery, a second altenator and impress the judges by running your equipmant right. If you burn your truck down at a bass competition the only thing youll get is laughed at and a spot on the nightly news.

 

I would NOT reccomend trying to bump up the voltage...Bad idea..Electronics are not to be fooled with because certain components are ONLY allowed to run within specific paramters and putting more current through them is never a good thing.
Now, I have as many amps sucked from my sytem as what you have displayed and I can run my stereo with no issue's on the stock 160A alt and stock battery. All I have is a Batcap300(equivilent to 100farad cap, cost ~$160).
Now, you may have the smaller 135A alt, but you will have major problems running your alt voltage up that high.
Personally, I would leave it alone and wait for the money to upgrade your alternator. They aren't $600 either. I seen a few online for $299-$399 for 200 and 220A one's. or you could evenb pick up a newer 160amp as they go super cheap on ebay for ~$60shipped