I removed my dinky little floor drains and put in the biggest thru-hulls I could find at 2-1/4". You can dump a couple 5g buckets in there now and it takes less than 5secs to drain out. I got tired of it getting swampy back there......

I used a Dremel with the sanding drum and that thing cuts through fiberglass like a hot knife through butter. If you decide to use the Dremel, wear a respirator. Its pretty dusty and you kinda resemble Tony Montana when you're done.......