I need Professional unbiased Help.

I drive a Falcon Au 2000 model currently with a stock audio system.

I recently made a trip to my nearest 'Alpine' Audio Store.

I was browsing at the highly rated 'SPR-17s' Type R speakers and subby with the alpine pdx-5 5/3 channel amplifier..

the amp puts out 300rms to the subby and 105rms to my 4 speakers.. the amp/subbys/and speakers cost $1500 all up AUS $$

I have talked to a few of my mates and spending that kind of money i should be able to get a great set of speakers/subby/amp and maybe even a head unit..

i'm fairly sure i will purchase just a clarion 150$ 2 pre-out head unit..

but i wanna know unbiasedly if i'm spending that kind of money are there other speakers i should look at/subbys? what not..

also i have a gas tank in the back of my car.. and i understand that can stuff up the sound of your sub, but would under seat subs work or ?

and would i get a better sounding system with clarion splits or focal splits? just wanna know how highly rated the type r system is

Cheers.