IMHO: It's a matter of time and intent. If often used as a road car and in the coming few years it would have an impact on value. Longer term this becomes less of an issues as old satnavs are clearly inferior to any iPhone navigation...
I purpously specked my 7gt3 without sat nav for two reasons, nothing dates a car more than an old audio/sat nav system and it saved me a good bit of money. As said by another poster go for iphone sat nav or a garmin
Chopped my old one in without nav and it took the OPC over 6 months and a 10k price reduction to move it. I know the nav wasent the sole reason for it not selling, but I'm sure it contributed towards it. It was a lovely car....
Personally I have a GT3 and want to move to a GT3 RS but without a satnav. As track cars their is no need for satnav. Extra weight and nothing I cannot accomplish without a map.
Think the market may wake up to this now that the smartphone thing is so good. All you need is an aux in, iphone/z10/android/ipad and a brodit mount and away you go.
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