My 3 best friends are my Jet dual hammer heavy duty 500ft-lbs 1/2" drive impact gun, my Chicago Pneumatics 30ft-lbs 1/4" drive impact gun, and my 60gallon Sanford air compressor
The only bolt that has ever stymied my Jet is the 'bad ass bolt', the foot long monster that holds the lateral links to the rear knuckle on Imprezas and Legacys.
The CP 1/4" drive is a dream for putting together interiors, electrical (starters/alternators) and synching up engine parts before you apply torque, it's fast, quiet, and doesn't apply a lateral load to your hand. I hate air ratchets because if the bolt decides to stick, your hand instinctively migrates to the sharpest, dirtiest and rustiest piece of metal within striking distance.