Hey, I also have the Shawn Lane signature and let me explain 2 things.
The reason the guitar sounds or feels thin is because of the Gauge 9 strings (super floppy and light gauge) AND the pickups are in fact very single-coily. The Dimarzio Air Classics are a low output, PAF style very bright wind with a scooped sounding Alnico 5 magnet. To top it off it is an 'airbucker', meaning they keep a gap between the magnet from touching the pole pieces inside the pickup which results in a squishy, twangy single coil kind of vibe and reduces some of the bass and punch/output. What I would suggest is keep the Neck pickup, and upgrade the Bridge Pickup to something a little fatter. 'AIR' pickups work best in the Neck position but in the Bridge they end up being too soft with a lack of punch. I dont care what the dimarzio description says on the website... THESE PICKUPS ARE SCOOPED, VINTAGE SOUNDING WITH A LACK OF BASS/MIDS. I think they are still quite good pickups but I have changed the bridge for a NORTON in my Shawn Lane.
I suggest you pick one of the following pickups (ranging from medium to high output depnding what music you play)
- Dimarzio AT-1 (Andy timmons sig pickup, fat vocal pickup, similar to a JB but warmer & with treble spike)
- Dimarzio Norton (Literally the perfect pickup for 80s rock / early van halen / Winger / Dokken etc. Tight bass, nice mids and a good dose treble with an alnico 5 magnet to use in warmer bodies/scales like the shawn lane). My personal recommendation for this guitar !!
- Dimarzio Transition ( Steve Lukather sig pickup - Fantastic Sound. Less vocal than the AT 1 and a little hotter with a wider frequency range . Ceramic magnet BUT doesnt feel too stiff and shrill like most other ceramics)
-Dimarzio Super Distortion (HUGE sound. Bright and also bassy with a huge thunderous chunk. Dimarzio's first ever and most famour pickup) Perfect into a cranked Marshall amp.
Swap the Bridge Pickup out AND use a set of 10-52 strings ! You can also raise the bridge / action just a tiny bit as well, this would help everything breathe a little better and less fret slapping sound. Trust me, you'll feel like you have a completely new guitar! Good luck and enjoy it, this is such a cool unique instrument !!
(p.s If you're confident enough you can also install a Tremolo stopper (FU-Tone.com) in the rear cavity which will make your trem DIVE ONLY instead of fully floating . This will increase sustain by the bridge/block contacting the body directly and hence resonate much more than a standard floating trem system.)