Is200 Stereo Install - Confused!

[iaind]

Hi guys, I know this gets asked a fair bit, but I'm yet to find a definitive answer.

My car is an 05 SportCross which has the separate amp - instead of the 2 6x9s that the saloon has, this has a sub and 2 tweeters in the boot. I primarily use the existing stereo with an xcarlink ipod interface, but I'm fed up of not having decent navigation of the iPod, so wanting to go aftermarket, something like the Alpine CDA-137BTi. I would go double din, but nothing sub 300 quid that I can find has rear USB and my iPod is tucked in the armrest.

So, the fascia - there's a few around but I dont want to have to modify something myself to keep the heated seats, so it looks like it's the autoleads fasica - are they really such a bad match in terms of finish?

Now, the wiring.... I was probably just going to use the amp bypass lead and then install a third party sub and amp if I needed it (or maybe even use a small third party amp on the stock sub), but I've read that the amp bypass lead will result in losing the OEM nav - can anyone confirm? So I could use the Metra TYTO-01, but have read conflicting reports about that one. Then there's the BeatSonic SLA-91AD http://www.beatsonicusa.com/beat-sonic-sla-91ad.html - this retains the use of the factory nav (despite saying it doesnt, have read threads which say otherwise) and amp but it's VERY expensive!!

I know there are schematics for a bypass module, I used to be quite handy with a soldering iron but really dont want to be doing that if I can avoid it.

Can someone clear this up, or am I just better sticking with what I've got?

[GME]

In order to use the nav with aftermarket head unit you will have to take your OEM head unit apart and keep the circuit board still connected which you can hide away in the glove box. Doing this will keep the circuit between the nav and OEM HU intakt. I've done it myself just to confirm this.