Cutting speaker holes

[andrzej77ff]

I am replacing all my cabin speakers with Kicker KM6200's. My current setup has 5" existing speaker holes and I need a 5 1/4" I believe. What is the best way to enlarge the speaker holes in fiberglass?

[30521v]

Air saw is better option but a jig saw works well

[chpthril]

Roto-Zip. Or, stack a 5.25 hole saw over a 5.0 and let the 5.0 act as the pilot guide.

[andrzej77ff]

Roto-zip as in a dremel tool? I don't have an air saw.

[strohlde]

I used a drum sander attachment for my drill, it was quite messy but it did a pretty good job. I wasn't having any luck finding an appropriate sized hole saw for a reasonable price. I think I picked up the drum sander kit for less than $10 at harbor freight.