Somewhat new to the glock family, so bear with me. I have the G27 and LOVE it. After shooting a friend's 10mm, I got the fever and came across an unbelievable deal on a new G29 Gen4 with Tru-Glo sites. Couldn't pass it up. Questions: 1. I've read many people upgrade the recoil spring, guide rod, and even the barrel on Glock 10mms. Is this necessary or recommended (if so, why?) for the Gen 4 G29 or are such upgrades just recommended on previous Gen's? I'm considering on carrying high velocity Underwood Ammo from the reviews I've read. If upgrades recommended, please list your recommended upgrades (incl brand names etc.,) and best places to obtain. 2. Even if upgrades are recommended (#1 above), would you be concerned with shooting Underwood Ammo with the stock G29 Gen4? 3. Is there a grip plug out yet for the G29 GEN4 to fill the space on bottom of grip? I haven't been able to find one for the Gen 4. Would the G30 plug fit? 4. I've heard the A&G magazine sleeve (for the G20 mag to use with G29) pinches and isn't the best. X-Grip seems to have good reviews, but again, I haven't seen one available for G29 Gen4. If not, any idea if X-Grip plans to make one for Gen4 G29 or other sleeve you would recommend that's available for Gen4?