
Where are you based? Can't see why the insurance should be a problem, really (for a Mustang).
The problem is that, for your budget, you have one of the best sports cars out there and discounting an auto means no big GTs.
The obvious option - Porsche 911 but you'll need to break your 10 year rule.
Left field suggestion Maserati 4200 - noise is worth it alone
It's not enough money to get you into a e9x M3 either and RS4 is a bit of a squeeze.
I think you'll have to up your budget or relax your age requirement to get any sort of upgrade.
Surrey, I got quotes around the time I got the Boxster and was told under 25 was just a blanket no and even between 25 and 30 would be a push as there had been a few s197 crashes.
I think I like the idea of a 335i manual with a remap the most but they're quite hard to find.

The cost of insurance isn't the issue - it's if I can get it!
335i's an interesting shout.

[ui]ICEMAN;25824849 said:The VX-R Monaro is a good shout IMO.
If he's even remotely concerned about the cost of insuring the Mustang then the Maserati 4200 is way off limits. Running costs on Italian exotics will make your eyes water and your wallet beg for surrender.
I did actually get a quote about 18 months ago and a Maserati 4200 was sub £1k. Repair bills might be slightly out of my league.
One of those big power VXR's might be worth test driving, along with a manual 335i with the view to a remap, I'll take a test drive of an Elise but I find the Boxster is close to my limit in terms of discomfort!
How much research have you done into mustang insurance? I can understand that major insurers and price comparison sites wouldn't quote you, but I bet if you rung a few specialists and asked on the owners forums you'd be able to get one insured.
[TW]Fox;25824858 said:Rubbish, you will be able to get it from somewhere. So it'll come down to the cost.
[TW]Fox;25824864 said:He'd be daft to own one without the cheap £40ish a month warranty so thats out as he hates warranties apparently. Somebody else paying for repairs isn't his thing
I suspect what he really means is that he hated the OPC warranty.
About 2/3 years ago I phoned 5-8 specialist insurers and all but one couldn't quote me. The one that did was something crazy like £8k.

[TW]Fox;25824871 said:As somebody else spotted you seem thoroughly miserable and unenthusiastic about buying a different car, almost as unenthusiastic as you are about your existing one.
What about a £6k Honda S2000 and a new hobby with the rest of the change?