My 21 sounded better also it seems to me than my 24 . I have the Kicker sub in the 24 like I had in the 21 it would rattle the rear view mirror and hud display not so much with the 24 kinda disappointed for sureyou are 100% spot on with ZR2 Bose in the 1500. it stinks. i had Bose in my 21 sierra denali and it was awesome. i replaced my rear door speakers and noticed 50% better sound. some have added GM kicker sub with good results, others complete tearout. use search for specifics.