hi there its time to update the gp audio.. I want a subwoofer in the boot connected to a new headunit.. but i still want steering controls. I know there are various adapters etc but still a bit unsure. so any advice on whoch cd player to buy and sub to buy? and also which adapters

Connects2 is your best bet for the adaptor and they work on most of the popular branded HU's.
AS for sub etc what sort of budget are we looking at?

well not sure to be honest.. ive got a JBL SUB and amp lying around so dont know whether to just buy steering adapter, wiring kit and have it fitted along with a new head unit. I want a heada unit that lights up orange similarly to the coloour of the dash etc. Ive seen an alpine one but unsure.

JBL are pretty good so if you already have the stuff i would stick with that.
Alpine are very good and are compatible with the steering controls with the adaptor.
Are you not worried that adding a sub on the stock speakers is going to over power them a little.

erm... not too worried to be honest as the cd players nowadays have an EQ so can set bass on the sub and the speakers can be boosted with mids n highs.

The eq on a HU will send the same too all speakers as it affects the signal that is set to the speaker outputs and RCA outputs so reduce the bass on the HU and you will also lower the bass signal to the sub.
When doing this there will always be the temptation to increase the volume on the gain, but the gain is not a volume setting it should me matched to the preout voltage from your HU. This will cause clip and if you dont know Clip is the squaring/flattening of the waves of the sound which is actually what distortion is and can cause lots of problems. Also if you have the EQ settings on anything other than flat on the HU your are increasing the chance of signal clip again with problems.

Some people use X-overs on the speakers run off the HU to block the lower notes that will make them distorst., these are just a sequence of capacitors strapped together to provide the desired resistance to filter certain frequencies called High Pass Filters (HPF)

True the gain is not a volume control, however if the gain is set lower so the sub does not overpower the front speakers then it will not cause damage. It will just mean that the sub is not fully efficient and therefore plays quieter. If you have no output control for the sub on the headunit then I would suggest this is the way to go. Ultimately of course to improve the SQ and volume, upgrade the front speakers and power them from a quality two channel amp.

another option to consider is keep your standard head unti and add a sound processor, look at JL cleansweep, RF 3sixty.1, or Alpine pxe h650, similar price to head units, but same quality plus no messing with dash, steering controls etc.

If you really want to do a sound system in a Grande I would upgrade the headunit. Its not that hard to do you can buy a headunit with usb port and bluetooth and it all works fine. And will make the standard speakers sound so much better. And will allow better sound quailty when you add a sub and amps.

will those signal processors accept pre outs? what about rremote leads will that still have to be wired to ignition?

Stu the standard speakers wont be over powered by a JBL as they are pretty decent when HU is uprated. Not brilliant but decent. Alpines have separate Subwoofer control on them anyway so you can adjust how much bass you get from it anyway

Sorry my bad i was thinking of my car because im splitting one RCA so the sub out affects everything

so an alpine head unit with the jbl sub would be ample afterall

Yeah it would be fine. But dont buy from abroad.

I think a proper update would need the front speakers replacing.

replaced mine this weekend with a nice set of components I got running of an amp in the boot and the difference is absolutely night and day, Its not actually that hard

I know Ive got some JL comps in mine and got the amp at home waiting to go in

word of advice mat, I couldnt actually find a way to get the speaker wire inside the car from the door cards, there is no grommet on the car side, there is on the door however.

What I did and it seems to be ok fingers crossed lol, i ran it under the door seal, I shoved the seal on with some force, obviously there is a little bump and when the lower trim is put back on you cant tell

ive kept my standard head unit. all ive used is a kicker zx700.5. it runs off the signal from the speaker wires once the rca's are spliced into them but has to be a kicker wirein kit. uprated front speaker and tweeters, 800 watt 12 inch kicker sub, sounds better than my old system in my old car and i still keep my blue and me and wheel controls.

soudns good fella, i would suggest saving up and buying a sexy new HU with bluetooth though and getting all those lovely speakers amped

I cant see any problem with what he has done. Newer cars dont need aftermarket HU's its beter to get sound processor.