Any 4x6 speaker just doesn't have enough kick in it for you to notice the particular speaker upfront. The 5.25 however does somewhat and you can hear the different between the two speakers.
There is consoles that came in jeeps that had the 7 speaker setup from the factory which had the sub right inside the console. I've seen a guide on here before how a guy turned his ordinary console into a sub one. Or you can just look on the classifieds and find a console that is sub ready?
I do know that the stock sub in the console is not that good tho and also recall seeing a thread of how some members actually upgrade the stock sub from the console to something aftermarket.
Also you wouldn't need an amp if you were to upgrade your front and rear speakers. I have 5.25 upfront and 6.5 in the rear, no issues and for me it sounds great.
Sent from the I-device using an APP
An amp makes ALL the difference in the world. I have a small amp (KTP-445) that only puts out 45 watts RMS per channel but it made a HUGE difference in my 5.25 / 6.5 Polk combo. If you drive with the top and/or doors off above 35 MPH you're really going to need an amp. Even at low volumes it made a big difference in mine. The stock head unit sounded like crap through nice speakers. I tried it but didn't tolerate it long at all.
2005 LJ, NSG-370 6-spd (close-ratio), 3.73's, three tops incl. custom Sunrider-Safari top, 38"x22" hardtop sunroof, OME 2.5", JKS 1.25 BL/1.0 MML, seats 2"^, 285/75/16 Duratracs, Ion 171's (16x8), Alpine CDE135-BT/KTP-445/Polk521Db/650Db, full soft/hard doors, Harley L.Stms, "I swear my Jeep is staying stock"