I'm sorry but you fail.
You have stated you are living with your fiance at her parents house.
fiance turns in to wife (about same time sex turns to occasionally)
fiance turning in to wife means wedding.
20 years old, $25K saved, working in current job for 6mths means that after wedding you will be left with nothing.
You'll be creating threads about petrol prices in no time and asking what people get ou tof their RB20's per tank of fuel.
Look mate I may sound like an arsehole (which is usual) but you really haven't experienced "life" as yet.
sure you can pay the loan back to the bank at your current wage and situation.
where you gonna live when you get married?
you'll be renting.
rent = about 300-400 per week.
most people also require food. - $100 - 200 per week.
when you rent, you'll find that at night times, you'll want tto turn lights on. and possibly the stove for cooking of food.
month later electricity bill comes.
you'll want to ring mum and dad for comfort about the cost of living = house phone bill
you'll want to be contactable when your out = mobile phone bill.
you'll want access to the intraweb to argue with realistic idiots like me = ADSL bill (possibly dial up by this stage)
How about some furniture to sit on and sleep on in your new unit? = Fantastic furniture bill
perhaps a fridge and other applicances to store and cook the food = Good Guys bill
how do your "EASY" car loan repayments looking now?
I sound like an old man and compared to you I guess I am.
but it's the truth.
it costs money to own these cars.
it costs alot more to maintain them.
it costs even more than that to modify them.
it costs even morer than the more before this more to make double the stock power.
you want 5 times the stock power.
Welcome to reality.