Outer Limits 4x4 Board

I just bought some new 6.5 inch splits for the shopping trolley (4runner). Misses wont let me install em and the amp will need a retune anyway.
I bought my speakers from JB HIFI in cantberra and i was going to get them put in by JB HIFI in Parra. Is this a bad move? should i take it somewhere else?

the bit that has me confused is the crossover. It can be either 1db or -3db. its going to the drivein alot so i really dont know what to ask for with this?. Either way its gunna be better than the 4 inch splits atm

Thanks guys and gals

I beleive the 1 or 3 dB controls how much volume is sent to the tweeter. So the higher will give you more treble from the tweeter. It depends on where you position the speakers. If the 6" speaker is in the lower portion of the door and the tweeter is on say the dash, you set it to the lowest setting, or there will be too much treble produced by the tweeter. If they are both mounted low, set it to the higher one. It doesn't effect things overly though mate.
The difference from 4" to 6" is enormous.. best thing I ever did to mine.

JB is always ok for installation up my way.. whatever people recommend is usually good.

jb's in parra is fine matey.. use them to buy and in some cases install all my shit. very willing to wheel and deal on prices too so dont buy nothing sticker price..even at sale time.

the done the install on my front 6 1/2inch splits (mb quart). cut away the factory gq speaker cover as i have power windows and spaced speakers out.. splits mounted on a piller. sounds sweet with mb quart 6x9's in the back all powered by kicker 800watt 4 channel amp.