I'm upgrading my sound system and I don't have any speakers up front. I want to add some JLA 6.5's in front up high so I can actually hear something over the wind noise at 80. I have just enough room and depth to add the speakers right next to my controls. It's a reinforced fiberglass and gel coat surface. Looking for recommendations on cutting a 5.25" hole without making a mess. Also upgrading the rears and looking for recommendations on opening those holes as well. I'm opening the small round holes another 1/2" for JLA 7's and the 6x9 openings are going to be replaced with 10" subs. You can see the template in the first picture, I will be putting the speaker forward of where the template is at. It's a little tight and the fiberglass and wood backing is too thick for a roto-zip. I don't think my electric scroll saw will get close enough to get the bottom of the hole. I was thinking about a small body saw. But I don't want to tear up the gel coat finish with a reciprocating saw. Appreciate any ideas.

I always just put a few layers of masking tape down then used fine tooth blades in my hand held jig saw.
Took my time and kept sharp blades.

Use a RotoZip TILE blade/bit, and it will work fine. Just move smooth and swiftly, so it doesn't overhead and brake the bit. I cut all of my speaker holes with exactly that.

It looks like you have some decent room there. But if if were me, I'd go as far forward as possible. I later upgraded to a coax speaker that was a bit taller outside of the mount, and then a billet speaker grille. That made the whole thing stick out from the fiberglass about an inch. Occasionally my hand would rub the speaker grille when using the controls.

You could also pull the wheel off and consider using a hole saw.

Roto Zip, Dremel with roto zip type bit, or hole saw.

https://www.mscdirect.com/product/details/06560551

Trepanning tool like this is the only thing I've ever used for large holes.

5.5, 6 or 6.5 hole saw

I actually found a 51/4" hole saw at Lowes online, guess I've been looking in the wrong place. Didn't know that they made a tile bit for the Roto-zip I will look for them. I'm thinking I will put the speaker in the middle, as the throttle is usually at one end or the other, doesn't spend much time in the middle. That way my hand doesn't block the sound, LOL. How hard is it to follow a line with the Roto-Zip? As the rears already have openings I will need to enlarge them for the new speakers. I even thought about making wood templates to trace with the Roto-Zip. I can't afford to make a mistake.

I've always (for 20yrs in the audio business) used either the Exact Hole Saw for the job...or a pneumatic Body Saw to cut all holes...Great accuracy and predictability and unlike a rotozip ...the blade never darts off path..(Don't get me wrong, used Rotozip in the past and sometimes still do for minor trimming)
Just my 2cnts

Its not bad. For expanding bigger holes like that, I've just use a jig saw and error on the small side then used a drum rasp to get the hole exact https://www.grainger.com/product/29U...P7A1P:20501231

^
Spoken For Truth. A drum rasp like Griff shows or an abrasive drum is your friend in these situations. I still prefer the trepanning tool, you can pick one up for only a few bucks. I've had mixed results with the RotoZip, you just have to be careful. As you note...you simply CAN'T fawk that area up and live with yourself...