Quote:
Originally posted by RJ:
Quote:
Originally posted by J.D.M.:
[b]The only concern is not to expect much horsepower in return. A number of years ago a Mustang Mag dynoed aftermarket hearders on a 5.0 and the swap neted only 1 additional horsepower on a 225 horse motor. So without an intake, or cat back system, please don't look for much. Headers were all the rage for choked 1970's performance cars, but the 2003 and up X's have a pretty decent factory exhaust. If anything, the Y pipe after the headers needs the help.
Don't know about the X, but the 5.0 example is an extreme one. Most 5.0s with catbacks will dyno about 10 - 15 on shorty headers and 20 hp on full lengths.

Age is really not an indication of header potential. The LS1 Camaros routinely dyno 30+ from long tubes. The LS7 Z06 dynoed 50 hp higher from only long tube headers, exhaust, and K&N.

How long are these SLR headers btw?[/b]
Sorry, got to defend my post, the article I was talking about dynoed the headers on a bone stock 5.0 without a cat-back system. On the other hand GM cars have always landed huge power gains when the exhaust was opened up. They traditionally have some of the most restrictive exhaust systems. You make a good point, a person probably could get some serious numbers on GMs. I just don't want someone to purchase headers thinking that it will solve all the ills of the Xterra's pre '05 power issues. Nissan's own web site credits their $600 cat-back system with 3.7 additional horsepower, not a lot of bang for the buck if you know what I mean.