I did exactly that and it made it come alive! The sub woofer now sounds as good as the original. I have been beating on it for over a week now and no strange noises like the voice coil bottoming out. I can fully recommend this as a replacement driver for the factory sub with a bit more handling power.
Thank you for the advice!
Glad it worked out. AFAIK: you are among the very few who have reused the factory enclosure - stuffing it with a high quality driver. Your project may give hope to others who don't care to tackle the larger project of building a new box.
There's a long held belief the the Pioneer designed enclosure simply cannot rival a more traditional enclosure constructed of MDF, ETC. Part and parcel to that belief is no shallow driver (that would fit) in the OEM enclosure is worth the effort cramming into a lousy plastic box.
I'm not in that club. I've measured the OEM sub with steady state 40hz sine waves, white & pink noise, beat on it mercilessly with <10X the power it *should* be able to handle. I remain impressed with its musicality. Said it before, repeating now: the OEM sub isn't going to shake your back bone or part your hair with unrealistic bass that can be heard from 2 block away - it lacks real authority much below 40hz, but what it IS is a competent performer providing definitive low frequency augmentation to even the finest front door low/mid-low frequency drivers.
Beat on that bad boy some more and report back, would you? Safe guess there are forum members here who will follow your path as their OEM bass drivers begin failing with age.
Curious: did you keep the flared port tube in place?