I have been going round and round with my local stereo installers and I am using that term loosly. If anyone has upgraded a late model 04/05 quad cab with the Infinity system I would appreciate a few pointers. I can't even get these guys to agree on the following points: the amp is under the dash, the amp is in the doors--you need to run seperate components for the front doors and the dash mounted tweeters with a crossover, you don't have to do that at all just put 6X9's in the door and leave the tweeters in the dash unhooked-- you can power the existing dash mounted tweeters with the head unit but you need a new 4 channel amp to power all the other speakers--you can run an aftermarket head unit with the amp wire enabling the infinity amp and speakers and it will sound GREAT, you have to throw the entire system away and spend big money--so can anyone help me to make heads or tails out of this?? it would be nice to have some ideas from someone who doesn't stand to profit from the install--thanks