i had a 350z, went for a CTR, then came back for a 350z HR
the 350xz costs me £20 a week more petrol, £200 more a year tax and the insurance is same... id rather pay £100 a month extra and have a zed... yeah u might have to change tyres, it may cost £50-100 more e.t.c.
basically, it hardly costs much more to run a zed so keep it!
oh and im 27 and have a mortgage/council tax/sky all the bills and am a london bus driver and still manage im sure u can