Hello I'm going to regelcoat my engine bay in my formula. Was looking at the ES-100 spraygun was wondering if there is something else I should consider. Thanks

harbor freight , drill it out as big as you can , search glassdave posts
ES100 will take forever.

Dump gun will leave a very rough surface. I found that a harbor freight old school cup gun worked the best. Tried the HVLP with the tip drilled but still had a lot of orange peel. To get it smooth you will have to think the gell with something... Then you can shoot with a paint gun.

I've been using the 3M accuspray PPS set up with the red 2mm tips.
Clean up is a breeze and the pressure cups let you spray in any position.
My best results were with using 50% Duratec high gloss additive mixed in the gel.

for smoothing out a bilge (and its a sh!t ton of work no matter the method) i roll on raw gel as heavy as i can (float the roller) and give it a good coat of PVA let that cure and sand the heck out of it, repeat this process a few dozen times (lol not really but you may need to do it a couple times pending how bad it is or how smooth you want to go) when you get to a point your happy with the finish and it is fully covered after final sanding then you move to a gun with the gel/Duratech mixed at 50/50 or i have also finaled out with roll and tipped AwlGrip but truth be told you dont really need to tip it if you take your time (it likes to be put on thin) . Raw gel will give you a pretty durable finish maybe not quite as shiny as AwlGrip. It really just depends on what kinda final result your after. Bilges are an absolute endless project seems like at times . . . sanding . . . . more sanding . . . . devils in the details for sure

I used this for my transom:

C.A. Technologies - Conventional

Jaguar 100C

Don't use gel coat. It always looks like crap and gets dirty so easily. Buy a decent single stage paint and paint it. It'll look better longer and much easier to clean.