xviper

I think they tell you that because most people would break the electrode off when they tried to change the gap. It is VERY delicate and you must not touch the center one with much force. You must use a feeler gauge carefully and if they need to be changed, you need to use a device that grips the side electrode without touching the center one. The gap for a boosted application should be in the 0.032" to 0.035" range (give or take). If you're not on boost constantly, a wider gap is better.

xviper

These were the first plugs I tried when I installed my Vortech. Almost everyone recommended these and raved about them. The car ran OK for several months, then suddenly developed a high rpm miss that was quite disconcerting. I then went to copper racing plugs. Those worked exceptionally well but didn't last much longer than about 5000 miles, at which time, the car started to smoke quite badly when idling for extended periods of time (as in waiting at border crossings). Once changed, the smoking immediately stopped. I still use the copper plugs but I change them out often. Generally, I stick with OEM plugs. These work well and seem to last a long time.
As for you inability to rev beyond 7K, you should double check all your splices. If you've spliced into the wrong wire, this could also create a problem. I found that working in cramp quarters, all those ECU wires can be confusing and some of them are color coded so closely that it's not hard to pick the wrong one. You may not spliced into the wire that sends the MAP signal to the ECU. If the ECU sees boost, it won't rev, but that's only one thing that can have such an effect.