quick tip for the downpipe, just remove the oil cooler but make sure you have new o-rings on hand. You'll have to get them from toyota, they arent expensive so dont sweat having to call the stealership. By just removing the oil cooler you give yourself instant access to all the bolts holding the downpipe on. That job is easy as pie. The only other oddball thing you need for that is the socket for the nut on the oil cooler, I cant remember how big it is, but its rather huge. Search around I know the size has been posted.
As far as the mani is concerned, I mean tubulars are great, but with whats already been accomplished on the stocker I just dont see the point until your breaking that 350-400 power range. Maybe even more.