I have found (at least with privilage) that the price hike for mods is in relation to the percentage increase of the mods. Under 10% for example no change. So I fitted a induction kit and exhaust for no increase (in premium). Of course these alone without a remap will give very little noticable change in performane in the real world. But they will sound cool. And of course you can replace em with the oem parts very easy and sell the parts for a few quid on the forums. A win win situation. Of course you can fit an LSD you will need to declare but again when I spoke to my insurers there was no increase. If I were you I would get an LSD, fast road set up/geometry check. A hondata K-Pro, exhaust and induction iether an AEM or GruppM. with similar mods Carl (N77), as shown in the new J Tuner magazine at the CTR group thrash got very good figures, sub 6 seconds to 60 and around 14 seconds 1/4 mile. Get the mag to see a few modding ideas.
The above would tie you over whilst the new 'R' comes out and will be very easy to sell, and take minimum effort (appart from the lsd) to remove. The LSD will, if not add value, help in a sale such is the benefits of having one.