as you said you still want to have some fun, enjoy your car for another year, R33 is a good car there are lots of potential, do crazy stuff, wide body, full rebuild etc etc, for another year.
You can have fun but of course also do realize that time is running out, what age do you intend to get married? 26-27? and by 30 probably 1 or 2 kids? the moment you have children that is the worst investment possible. Your financial burdens increases as your partner have to stay home for the children
Now, You may realize that you need at least 20% deposit on house and at the current rate, a decent house ($400k) requires about 80k deposit. for most people of our age that requires about two years to build. by then we'd be 25, just a year or two before the marriage.
in that two years you probably have to spend money on your future wife and maintenance for your super modified R33, and when you get married you'll need at least $30k to please your wife. those two years you can't save much, $50k tops?
$400k - $80k deposit -$50k savings and still owe the bank $270k. Not to mention the 7% or so interest each year. Then your children pops, paying for their medical bills, etc etc. will take at least another 7-8 years to finally cover the mortgage. Meaning 1/3 of your life will be in dept.
time is running out fast if you see further, I don't discourage spending money on the car for the time being. We are young we still need to enjoy, however having a loan for car is just not worth it. The future implications is too great, imagine on top of the 7% interest you have another 12-15% interest for personal loan. by the time you finish your mortgage, 1/2 of your life will be in dept.
do with what you have: "contentment is not the fulfillment of what you want, it is the realization of what you already have"