Tell me why my panel is good enough.
I'm VFR only, for now. Old school IFR plane. Don't use the stormscope. No GPS in the panel (iPhone 6plus with FF). Cracked plastic. Ugly placards. Mismatched radios.
Aww, I have a spot spot for these old configurations.
Hey, if you're VFR only, you really don't need a lot... that's the truth of the matter. Also, avionics are almost worthless the second you install them. They cost a mint, yet hardly add to the value of the aircraft at all. It's alway seemed crazy to me, but it's true.
Your panel actually has the framework of a pretty good IFR panel. An HSI is a really nice piece of equipment, something even my plane doesn't have until it gets its second G5 in March. And you don't use that Stormscope? I have the same WX-900, but it died last year and I'd like to replace it with a working-as-removed copy... want to sell yours?
You can step into the 21st century a couple of ways.
Plan A: Ultra budget
Given that you already have an HSI and whatnot, the ultra-budget method is to buy an inexpensive non-WAAS IFR GPS such as the KLN-94, which I flew for many years and always felt was under-appreciated for its capabilities. You could get one of those for $2000-$2500, figure another $1.5k to install assuming the cables for the antenna are still present from the former GPS. Looks like you have the last generation "gold standard" HSI which is the King KCS-55A, and that will talk to the KLN-94, no problem. (Your old CDI probably won't, if you have to shift that to the KX-155... you could just leave it hooked up to your old TKM radio though.)
Then, add one of the bargain basement ADS-B OUT solutions which piggyback on your existing transponder and have integrated WAAS. (I'd probably go with the GDL-82.) Build a Stratux for IN ($200 max) and your aircraft is transformed into /G, ADS-B OUT compliant.
Downside: this has no legs for growth. This will kick the can down the road a ways, but none of these are ideal long-term solutions. You're basically going to be increasing the budget for X number of flying hours to get to the point you have to start replacing this stuff. King doesn't make the screens for the KLN-94 anymore; when it dies, you'll have to find another used one to replace it, or ditch it. The KCS-55A has always been an expensive instrument to maintain, so expensive in fact that at the first signs of needing an overhaul you'd be much better suited with replacing it with a G5 HSI. And these piggyback ADS-B Out solutions are a bit of a kludge. I considered going that route myself, but if your transponder is old and needs to be replaced anyway, well...
Anyway, this turns your ship into a real, honest-to-goodness IFR platform that you can do some real work in. No LPV, but you can shoot GPS approaches, file /G for enroute, and enjoy the benefits of ADS-B Out (not to mention be compliant with the 2020 mandate.) I'd estimate the all-in costs at around $7500-$8500, maybe less if you're handy and your avionics tech will let you do some of the work.
Plan B: Midlife Flyer
Nowadays, it's hard to justify the installation costs of going cheap. If you're going to tear the panel apart, most owners seem to find it makes the most sense to just swallow the pain pill and be done with it all in one fell swoop. But how far do you go?
The biggest bang for the buck improvements in safety and capability are, in my personal and very subjective opinion, all coming from Garmin these days. Garmin's current suite of low-cost offerings are designed to work together and give the panel room to grow as new technology is introduced.
To that end, you could drop a pair of G5s into your panel, one for ADI, one for HSI, sell or trade-in your old KCS-55A for a nominal cost reduction on the installation, and assuming your AP is rate-based -- it looks like it is -- you can ditch your entire vacuum system in the process, using your existing turn coordinator, which I believe your AP is referencing, as your backup to the G5. Of course the G5 HSI is also a reversionary mode option for the G5 ADI so you'll have a backup there already, making your system triple redundant with no need to for vacuum at all. That's a BIG safety and reliability upgrade.
You'll need a WAAS GPS. There are two ways to go in this Plan B category, either a Garmin 430W or a GTN 650. (I know there are other options here but given they don't play nicely with the G5s, I'm going to exclude them.) You can get a 430W for a little less than a 650... but not that much less. If it were my money, I'd go with the GTN 650 for the $2k-$3k delta in cost. That gets you into a current generation, completely badass WAAS Navigator that will go another 20-25 years into the future. The 430W is still popular but these things are getting reaaaallly long in the tooth and Garmin is sending end-of-life signals with upgrade/trade-in programs. So I'd be very hesitant to drop big bucks on a 430W at this point. Once the price drops below $5k they're a lot more attractive but that's still not the current market reality. Don't save a penny here to cost yourself a pound down the road, would be my advice. Just get the GTN.
(Incidentally, this was exactly my decision tree in late 2016. I obviously selected the GTN 650... no regrets, it's an amazing device.)
I'd keep the KX-155, still a nice radio, deep-six that old TKM, and replace the CDI which appears to be paired to the TKM with a KING KI-209 loc/GS CDI.
This leaves ADS-B... the Ferrari of the bunch for most piston GA airplanes is the Garmin GTX345. It's an all-in-one IN/OUT integrated solution that is both UAT and ES, incudes AHRS, and sends the data via bluetooth to your iPad or Android tablet. It will also portray the traffic and weather on the GTN 650. It's pretty much the bomb. But you could save a few bucks and get a 330ES. No AHRS or bluetooth there, but you can add a Stratus or Stratux for your "IN". It's slightly clunkier, but works and you could save a couple grand going that route.
You're looking at about $25k-$30k here.
Plan C: Ultimate Beastmaster
Easy, you're going to ditch everything and cut a whole new panel here. For PFD/MFD, Garmin TXi 10.6" display. You'll want a GTN750 with a GTN650 below it for Navigator #2. Remote a Garmin GMA350C audio panel and GTX345R to the GTN750 to clean up the amount of hardware in the panel. JPI EDM-900 engine monitor to replace your gauge cluster. Your mind can wander from here. This is a $60,000+ proposition, probably worth more than the entire airplane.
From a financial perspective, none of it makes sense... it would probably be cheaper, technically, to sell the whole airplane and buy one with the stuff you want installed. But, that kind of solution doesn't always fit, either. We get accustomed to our airplanes, the way we've maintained them, and so on. It took me years to get my airplane mechanically where I wanted... I can't imagine starting that process all over now. So I just upgraded my airplane to enjoy it. If that sounds like you, then follow an upgrade path that makes sense for you. It's really not about getting money back out of it, it's about spending the right money for the right amount of satisfaction and capability for a given time period.
