I have found some Premium Audio System door panels for my 97 GT Convertible. I am planning on buying the 4" speakes also. Doe anyone know if the wiring harness is already there for the added 4" speakers? Tim
Upgrade from 6 to 8 speaker - 6G Celicas Forums
it is not, you need an additional amp and a whole new wiring harness... which can easily be custom fitted... the 8" speaker harness goes to the 4", tweeters stay the same, and 8" woofers go to the new amp... i have it for sale if interested 
Breaking Axles...
I'm not sure if I want to take all that on. I like how it sounds now. But, how much? I took out my stock amp for the 6 speaker system and I am running them on the new head unit. Tim
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QUOTE (pittfirefighter @ Oct 28, 2009 - 2:29 PM) 
>it is not, you need an additional amp and a whole new wiring harness... which can easily be custom fitted... the 8" speaker harness goes to the 4", tweeters stay the same, and 8" woofers go to the new amp... i have it for sale if interested
well what you would want to do is what i did... my headunit ran my 4" and tweeters... i bought a four channel amp and used it to power the two eights and two channels bridged to power a sub in the hatch... sounded amazing
Breaking Axles...
That does sound like a good configuation. Thanks for the tip. Tim
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QUOTE (pittfirefighter @ Oct 28, 2009 - 7:31 PM)
>well what you would want to do is what i did... my headunit ran my 4" and tweeters... i bought a four channel amp and used it to power the two eights and two channels bridged to power a sub in the hatch... sounded amazing