On a GenIII with the regular MAF, you'll get the extra flow, but the difference won't be huge, as the maf's diameter limits the size no matter what tube you use. A short ram on a stock tune should be fine.
If you have a GenIV or are using a blade-style MAF, you'll run into erratic tuning issues. That maf has a sampling tube and expects certain volumes of air to meter.
Will you get "butt dyno" hp, probably not. You may notice a difference in sound.
I guess this is a good time to link a video. We switched my regular 4" short ram
"hot air" intake, for a longer intake and shielded intake box. Its still all based off of the ebay silverado intake kit, just with some work around it.