Has anyone out their ever added an amp to the stock head unit of an 04+ 4runner with good results no hiss or whine.I like the stock look but i was thinging of adding agood amp and speakers.

Just get a good in-line converter and you will be fine.

Easiest way to get a power boost is to simply replace the stock HU with a Scion head unit. It offers a substantial increase in amplifier power, and some interesting DSP options. You can find them on ebay in the $100 range.

i was running the factory jbl w/ the 6 in dash cd changer and installed an amp for 2 10 inch subs. i used a PAC Trunk-LOC line output converter with a built in remote power switch.
most oem radios do not have a remote power and causes the owner to run a separate wire by tapping into a 12 volt ignition or accessory, this is where you get the hiss, whine, or electrical interferance. and if you run your remote wire to an ignition or accesory you might get a big "THUMP" sound when turning your car on and off. the PAC Trunk-LOC converter has a soft turn on and off which means it fades the power on and off so no "THUMP".
it's real easy to install and comes with all the instructions. i got mine from ebay for about $35.00 shipped. just type in PAC trunk-loc.

good luck!!!