Hello. I hace audi s3 8l facelift with BOSE. I replaced Rns-d with Pioneer MVH-AV280BT. I made harness like pc9-410 and all is working great. Now i want to replace the stock sub and amp with aftrtmarket one. The sub i will use is Alpine SWR-8D4 I will get stealth box fom ebay for it. But i don't know how to wire it. I have to run a power cable from the battery to the amp. What about rca's? On my HU there are 2 seta of them and both are used for BOSE speakers. Is there any way to use stock installation from bose sub to get rca for my new amp?