The CD/Tape part of any HU will work fine, the cars in the US still run off 12v and have a negative ground just like we do. Where the HU plays DVD's you will most likely have a region 1 coded player and we have region 2 so you may not be able to play the DVDs you buy in HMV etc on it. The big difference though is that you will be unable to pick up many radio stations. In the US FM is broadcast with much wider steps between stations, so you may not be able to tune into your favourite station over here.

The biggest problem you will have though is warrenty, in short if anything goes wrong with the unit the UK arm of the manufacturer will more than likely refuse to fix it due to it being an import. This is probably the biggest drawback after the radio.

Two reasons both to do with the placement of them. 99% of the time they are placed on the rear shelf. so the sound is coming from behind you. How many of you would go to a concert and stand with your back to the group? The other problem is if you have a sub in the boot the air pressure behind the 6x9s will cause them to struggle and most likely distort slightly.

Not neccesarily, most of the non-standard sized stereos can be replaced by getting an adapter from a company such as autoleads. Many of the stereos are DIN size with just an odd size facia anyway. There are exceptions though the Mk 3 SEAT Ibiza being an example. With these cars the only way is to take your car to a good ICE Installer for advice, or ask on the ICECavern forums.

This only works for mids and subs but is a good way to check polarity if there is no other way.

First check that its not marked on the terminals usualy with either a red mark for + or the +/- is marked on. If not connect a short length of wire to each terminal. Take an AA size battery and connect the - terminal to one of the wires. Briefly touch the + of the battery to the other wire while watching the cone of the speaker.

When the cone of the speaker moves outwards the + of the battery is touching the + of the speaker.

The crossovers job is to split the frequency of the music to the speakers so that they only play the sounds they are capable of reproducing. So the bass isnt sent to the tweeters for example.

There are two types of crossover, the first is called a passive crossover, and these are generally packaged with a set of component speakers to filter the music between the mid and the tweeter. The other is an active crossover. These are either built into the amps, HU, or are a seperate item that filters the signals before the amps. The advantage of an active crossover is that it is generally adjustable and gives the amp less work to do. The dissadvantage is that you need a separate amp channel for each speaker.

The remote out on your HU will have a very low current rating. Normaly its safe to wire one or two amp remote feeds to it but any more than that and you risk damaging your HU. Never wire neons or fans etc off this feed. If you want to run those or you have more than two amps to run off this then you must install a relay.