After market Deep Spool options for 2015 Exist spinning reels?

Waiting for the spinning reel guys to chime in…

Heya, So there are definitely lots of options for you for both after-market spools and spools from the Real Four series. The great thing about the older mid-high-end Daiwa spinning reels was the RealFour project which allowed for the interchangeability of spools and handles between models labeled RealFour. 

Since you are looking to increase the spool capacity on a 15 Exist 2508 the main body is a 2500-sized reel. Therefore, it should accommodate a 2500 size spool; 2500, 2506, 2508, 2510. To increase spool capacity you would be looking at a 2500 or 2510 spool. 

This gives you a lot of options for spools. As an aftermarket spool you could look at the RCS air spools, sadly they sold out on hedgehog but you should be able to track one down in the second hand market. 

You could also look for a 15 Exist 2510 or 2500 spool, or any other RealFour spool. Luckily there are a lot of RealFour reels giving you an array of options. For a cheaper original spool you could look at a 15 luvias or 16 certate. 

Whilst I have never owned a 15 exist or had to increase spool capacity (I just have reels in the size I want), I made sure it works by putting my 16 certate 2510 spool onto my 50th anniversary 2506 reel and everything fits fine. 
I hope this helps.

Great information. Appreciate the feedback. Thanks

@keeping-it-reel good stuff Gabriel. 🤙🏼