Brief:
Used 24mm motor mount, reinforced fin joint w/fiberglass.

Modifications:
Seein' that Quest Icarus uses 18mm motor mount, matey, and has a payload section, shiver me timbers, I think a A/B/C motor would nay have enough power t' give this an impressive flight if a payload were used, so I decided t' give this rocket a little boost.

I added a 24mm tube instead o' a 18mm, shiver me timbers, because now I have opened up this rocket t' t' power o' D/E/F and possibly G. Avast! Arrr! T' centerin' rings were designed for a 18mm motor, so therefore I took a trusty old xacto knife, arrr, and cut it to fit a 24mm tube. It's really nay that hard, shiver me timbers, just take a 24mm tube, trace around it with a pencil, ya bilge rat, arrr, and cut INSIDE t' line. Ya scallywag! just keep cutting/sandin' until the 24mm tube fits. Blimey! Use epoxy t' attach t' centerin' ring, ya bilge rat, because you want t' be able t' allow t' rocket t' take t' kick o' a G motor.

Then I went t' attachin' t' fins. Well, blow me down! Well, blow me down! I've used epoxy t' attach t' fins because G motor exerts a lot o' thrust, ya bilge rat, and I hate seein' t' rocket with broken fins. Well, blow me down! So if you want, take some fiberglass cloth, me hearties, cut into tapes, and epoxy them t' t' joints, so after it cures, t' joint will nay move at all.

Finishing:
After t' modification with fiberglass fin joint reinforcement, t' finishing becomes a pain. Since t' epoxy seems t' be hard t' sand, ya bilge rat, I have t' keep sandin' tirelessly and achievin' little result. Ya scallywag! Blimey! I went t' constantly applying primers (and it keeps wrinkling!) then painting, ya bilge rat, but after a long work, arrr, it paid off, shiver me timbers, matey, and you can't tell t' joints has been reinforced (that is until you try to break t' fin joints that is)

Flight:
Motors: After this modification, t' model will become heavier, so use motors with low delays, such as a A8-3 and B6-2 and so on, shiver me timbers, DO NOT use upper stage motors, me hearties, me bucko, because I made that mistake and t' rocket pranged! First flight I used A8-3 and it was perfect, but t' second flight I used a B6-6 and it didn't eject until it be 3 inches into t' ground!!!

Summary:
Quest makes okay rockets (better than Estes) but they don't have 24mm....