What we researched for this specific generation: where an enclosure actually fits, what the factory speakers are, how the factory audio is wired, and which real builds and commercial products exist for it. Confidence badges say how well each figure is sourced — this is research, not manufacturer spec.
Body styles covered: 4-Door Sedan
These are researched envelopes, not a guarantee. Measure your own vehicle — the numbers here tell you what to expect, not what you have.
| Location | trunk, through existing opening |
|---|---|
| Outer bounding box | 36"W x 17"H x 34"/47"D |
| Known obstructions | None documented. DESIGN TO 34" OF DEPTH — the pair means the space tapers and the source does not identify which end is which, so the smaller figure is the safe one (catalog rule, now applied across eight vehicles with paired depth figures). The spread here is unusually wide at 13 inches, so the difference between the two readings matters more on this car than most; measure before committing to anything past 34". |
| Usable volume estimate | 4.5 ft³ |
Suggested configurations for this vehicle, not prescriptions. Run the numbers in the Box Builder before you buy anything.
| Subwoofers | Powered sub in the trunk |
|---|---|
| Box type | powered enclosure |
| Location | trunk |
| Subwoofers | 1x12" or 2x12" sealed |
|---|---|
| Box type | sealed |
| Location | trunk |
| Subwoofers | 2x12" or 1x18" ported — the source explicitly says this trunk holds massive boxes, and even at the conservative 34" depth there is room |
|---|---|
| Box type | ported |
| Location | trunk |
Sizes and depths below are what research turned up for this generation. Confirm against your own vehicle before cutting or ordering — trim levels vary.
| Factory speaker size | 6-3/4" woofers on BOTH base and Monsoon cars. Replaceable with 6-3/4", 5-1/4" or 6-1/2" — BUT THERE IS A HARD NUMERIC LIMIT: the replacement speaker's FRAME WIDTH CANNOT EXCEED 6.346". That is the single most checkable spec on this page and it rules out a lot of nominally-6-3/4" drivers. An adapter bracket is required for the smaller sizes. |
|---|---|
| Known obstructions | FRAME WIDTH CEILING OF 6.346" is the binding constraint — check the spec sheet, not the nominal size. Beyond that, some speakers require CUTTING OUT THE BACK of the plastic cup or mounting bracket, and depending on the driver you may also need to DRILL NEW SCREW HOLES in the bracket. The source is emphatic that base and Monsoon front doors are mechanically identical — "the same, but different," and the only difference is the badge. Tools: Phillips screwdriver, panel tool, 10mm socket, ratchet, extension. |
| Adapter bracket needed | Required for 5-1/4" and 6-1/2"; may additionally need the plastic cup cut and new holes drilled |
| Tweeter | In the DOOR PANEL, just above the woofer — note the split: the woofers mount to the door itself, the tweeters to the removable panel. Present on both base and Monsoon cars. Gently pry them out and disconnect once the panel is off; new component tweeters need hot glue, silicone or a universal backstrap to secure. |
| Factory speaker size | None — no rear-door speakers. The rear channels come from the rear deck. |
|---|---|
| Known obstructions | n/a |
| Adapter bracket needed | n/a |
| Factory amp / premium audio | Base: 6-speaker system. Optional MONSOON: 7 speakers, adding the centre dash speaker, plus a Monsoon-only AMPLIFIER mounted in the REAR DECK between the two rear speakers. The disassembly process is identical either way, and the front doors are mechanically the same on both. Where the two diverge sharply is the rear deck — the Monsoon amp drives dual-voice-coil 6x9s with bass and treble on separate wire pairs (see other_speaker_locations). A range of single-DIN and double-DIN receivers fit the dash. Replacing the receiver costs the factory XM satellite radio and the driver information centre's calendar function; the warning chime is a separate and much more serious matter, below. |
|---|---|
| Adding subs without a head-unit swap | Yes, and on a Monsoon car it is the cleaner path — leaving the factory head unit in place avoids the chime-adapter requirement entirely, while an aftermarket amp for the rear deck and a trunk sub addresses the actual sound. |
| Head unit | No replacement needed |
36"W x 17"H x 34"/47"D. The source's summary is that the Grand Prix has a great big trunk that will hold some pretty massive subwoofer boxes. The 47" figure is the largest single depth number. On Monsoon cars the factory amplifier lives in the rear deck rather than the trunk, so it does not eat into this space.
Each link opens the tool with this vehicle already selected.
Measure your own vehicle. Trim levels, factory subwoofer options, and mid-generation changes all move these numbers, and a box cut to a researched figure that does not match your truck is wasted wood. Where a badge reads Unconfirmed, treat the value as a starting point for your own measurement, not as an answer.