OK, well stuff I have cobbled together to see if I like a sub in the boot:

Alpine Type S 12" in fancy letterbox ported (bandpass?) box

Infinity ra7502 amp, Bridged rated at 220RMS at 4Ohms.

A problem i have is that the speaker is 2 x 4Ohm voild coils.

I can either get 8ohm or 2 Ohm depending on how i wire it.

Will using it at 8Ohms mean its severely underpowered and thus not a good exaple of how my car should sound?

Is running at 2Ohms likely to kill my amp?

Im not intending to go for silly volume and Im not sure which technique will be best.

Jono

You've got to make sure your amp will go down to 2 ohm or you will fry it eventually. If it does, it will give you a higher power output (obviously because the load on the amp is lower). 8 ohm would lessen the power output of the amp because it's driving a heavier load but I am pretty sure that it's not a case of doubling the impedence = half the power output as far as what you perceive in volume is concerned. At the end of the day, if your amp can only run at 8 ohms, you can at least try it and see how it sounds. It's easy to get wrapped up in figures rather than actual sound quality.

Third option is to not bridge the amp. and run each voicecoil separately.

running tm seperate aint happening mate. not a good thing to do at all.

if your worried about it then spen the extra couple quid, get a type R that is 2x2ohm

I have already acquired a cheap type S and box.

Im thinking that I might actually switch to a Sealed 10" sub, if the 12" is a bit boomy and not punchy enough.

Its not really boomy dance that i listen to, mostly guitar based stuff, but i do want to be able to feel the bass.

Ill try running it at 8Ohms, im sure it will be more than adequate anyway, and that way theres no way ill fry the amp.

Jono

running tm seperate aint happening mate. not a good thing to do at all.

if your worried about it then spen the extra couple quid' date=' get a type R that is 2x2ohm [/quote']

Erm.. Why?