The ER is brimming with potential, Nissan really corked her up, I think to be conservative for powertrain life. Stock the engine sucks and puts out about 172-174 whp, about the same as project pathfinder and it only does that on premium futel which it eats at an amazing rate.Adam said:
First off an AEM CAI steps it up around 15 whp! The stock air box is very restrictive.
Next the exhaust manifolds are really bad, in 2002 Nissan redesigned the VG exhaust maninfolds but they did not put them them on the ER.
Finaly the exhaust system sucks with a T juncture where the cylinder banks come together.
I would get the doug thorly headers used in project pathfinder and go to 2.5" mandrel bent tubing to a pefroated core straight trhough muffler, I recomend Magnaflow. This gets rid of the T-Juncture and the crappy manifolds.
I think the header, exhaust and CAI are good for at least 30 whp and proably more!
Finaly the engine suffers from really bad cams. They are babys for lift and duration. Some Nissan motorsports 256 cams will really wake her up to the tune of proably another 15 hp. Motorsports 262 will go even better but will have a lumpier idle.
JWT's S3 cams will work the best if you ahve a ligther 2wd truck and are not caring about towing torque as much. JWT's have the best top power by far.
I think cams, headers, exhaust and intake with a little tuning of fuelpressure and maybe an AFC will gain over 50 whp I think.