Bose system question

I have a 91 SE with a Bose system. I went to Circuit City today to purchase a wiring harness to use with my new HU, but the guy said to rewire instead because the harness won't do anything. Then, I talked to the guys at Fry's and Best Buy and they said that the harness should work. What should I do? o_O

(sorry, I don't know much about car audio) :(

Hey the harness will work fine. I used to sell car audio and it sounds good with the harness but you will lose some of the sharpsound through the harness, but it will work fine.

i also installed a new HU in my 92 SE and i heard nothing trough the speakers... and i used a harness form Crutchfield. its not the Bose harness though.. also another question, the rear 6x9's are bottom mounted right? but when i tried to unscrew them, the base with the amp is still there.. are there screws on top of the rear deck that need to come off first? .. any help would be great!..