Yeah, don't use the stock cup holders! The are poorly designed and poorly positioned right over your radio and HVAC units (where you don't want to spill anything), and won't securely hold most tall travel cups. I use Ultimate Cupholders in my 2003, which are adjustable and fit within easy reach and out of the way (they tuck up under the seam of the center console carpet. They cost more than other aftermarket units, but are worth it IMHO.
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www.ultimatecupholders.com]
But, I agree to check with a dismantler if you want to replace the OEM units.
Gary
2003 Boxster Base - Midnight Blue Metallic, Savanna Beige, Metropol Blue