Yes, you would have to replace the rear clip and tail lights, the side skirts, front clip, headlight covers, turn signals, and c-pillar covers. If you can find the parts, it can be done.
Weight really depends on options your ES has. Does it have the ECS, digital climate control, power leather seats (drivers side)?? The body panels wouldn't make a huge difference, but the are "larger" than the ES ones so they would weigh a little more.
Just a guess for what used parts would cost...Side skirts, 200 to 300$, front clip 300$, rear clip 300$, sail panel (c pillar) 150$, front and rear turn signals, 300$, headlight covers (flip ups) 100$. I don't really know for sure as I have never priced any body parts.
I read somewhere that the RT was actually about 400 lbs heavier than an ES. The parts are on Ebay I would like to do the same thing I hate the body side mouldings on the ES. I wonder if some one makes aftermarket solid red or whatever color so you can get rid of the black faded ones?
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Red ES 17" Momo Corse Rims /Toyo Tires /custom exhaust/Custom Seats. Even the dings are custom.
Jakster, the service manual says there is about a 200lbs difference. Not a lot, but enough.
Most people do have the black stripes painted like t4dude's picture.