I pulled the trigger and ordered JBA long tube headers in stainless steel and URD o2 simulator from URD. I wanted to free up the exhaust in order to gain HP and TQ. By looking at the dyno graph there is only power loss below 2.8k rpm. Above 2.8k rpm the headers SHINE! By 3.68 rpm, there is a torque gain of 24WTQ and 17whp! The headers gain 4whp and 12wtq. I was especially intrigued by the gains between 2.8k rpm and 4.2k rpm which i thought could help when towing and getting up to speed or passing.
For the price of $468 I paid shipped from URD for JBA headers, gaskets and o2 simulator, the headers are definitely the best N/A performance mod for the 1GR.
Th JBA headers appear to be good quality. Fit is OK, I was unable to line up the headers with the header support brackets which bolt to the bottom of the header where the header connects to the midpipe.
One thing to be aware of is that the headers come with four holes for the o2 sensors, you will only be using two holes. The headers don't come with plugs for the holes. The plugs have to be ordered online, they are impossible to source locally.
Now for the install instructions. Below are Instructions which came with the headers just for reference. I didn't follow these instructions very closely, because many of the steps are unnecessary.
Now for my instructions;
1, securely jack the truck up and put on jackstands
2, remove front wheels
3, remove mud guards inside wheel wells
4, unplug all oxygen sensors (total of 4)
5, remove Y pipe - two 14mm bolts hold it to the exhaust and four 14mm nuts hold it to headers (two nuts on each exhaust manifold)
6, remove 14mm bolt holding exhaust manifold to brace. Bolt located on the bottom of the exhaust manifolds same spot where the ypipe connects to the exhaust manifold
7, remove nuts holding stock exhaust manifold to the heads of the engine all nuts are accessible through the wheel well (6nuts on each side)
8, remove stock exhaust manifolds, it requires little twisting because the exhaust manifolds get hold up on the brace at the bottom
9, remove brace held by two 14mm bolts on each side, my headers didnt line up with the brace
10, remove old exhaust manifold gaskets
11, install new header gaskets which came with headers
12, instal headers and hand tighten all header nuts (6 on each side)
13, tighten header nuts, work from inside out alternating top to bottom, once all nuts are tight, tighten them again in the same fashion to make sure the nuts are tight and the headers wont leak.
14, re-install Ypipe, use the nuts & bolts which came with the headers. two bolts & nuts per side they are 15mm
15, reinstall ypipe
16, plug in all 4 o2 sensors
17, install URD o2 simulator, i used zip ties to secure its harness and secured the unit to transmission mount
18, re-install wheels
19, safely lower truck & enjoy new headers!
Now for some pictures of my headers;