I recently received a PM from a new member in Panama on the S&S headers for 98-00 LS400s. I had posted my recently plans a few months back on CL and thought I had done so here as well but for some reason no. Here is the posting I did on CL followed by new member thjakits PM (reposted with his permission)
Well gang, believe it or not I do NOT have the S&S headers.
The 98-00 LS400 manifolds are longer and the cat flanges are rotated relative to the GS400 manifolds that the S&S headers were designed to directly replace.
My set of headers is currently at Jet Hot and should be in my hands in about 2 weeks. I have decided to modify the headers rather than the Y pipe. This keeps the car serviceable with factory parts at any time. I will also be creating a new Y pipe but it will be a direct bolt in fit to the factory.
Modifying the headers requires that I jig the stock manifolds, cut the cat flange off the S&S headers, extend and re-weld the then extended flange in the correct position for the factory installation.
By doing this I will have the ability to modify headers (by request and arrangement) for any one else that is interested in this same approach.
I will also post pictures and progress as I move through this project.
The headers should generate the same HP and TQ increases that the GS400s see roughly 15-20 RWHP and RWTQ and improving engine response, power under the curve, feel and the fun factor.
For a Y pipe upgrade I plan on building a direct bolt in replacement that will replace the stocker which unlike the GS has a bottleneck resonator and ugly cut and slash sections at the cat outlets. The plan is a part that will be a direct replacement. I also plan on a second Y pipe that will replace the center muffler section and bolt in and use the stock rear mufflers. These parts will give a number of options for power and noise levels. I will build them to suit my taste for relatively quiet operation, preserving low end power/torque and allowing peak possible power/torque.
Depending on how hard this project turns out to be I may consider making other copies.
Stay tuned.
Well gang, believe it or not I do NOT have the S&S headers.
The 98-00 LS400 manifolds are longer and the cat flanges are rotated relative to the GS400 manifolds that the S&S headers were designed to directly replace.
My set of headers is currently at Jet Hot and should be in my hands in about 2 weeks. I have decided to modify the headers rather than the Y pipe. This keeps the car serviceable with factory parts at any time. I will also be creating a new Y pipe but it will be a direct bolt in fit to the factory.
Modifying the headers requires that I jig the stock manifolds, cut the cat flange off the S&S headers, extend and re-weld the then extended flange in the correct position for the factory installation.
By doing this I will have the ability to modify headers (by request and arrangement) for any one else that is interested in this same approach.
I will also post pictures and progress as I move through this project.
The headers should generate the same HP and TQ increases that the GS400s see roughly 15-20 RWHP and RWTQ and improving engine response, power under the curve, feel and the fun factor.
For a Y pipe upgrade I plan on building a direct bolt in replacement that will replace the stocker which unlike the GS has a bottleneck resonator and ugly cut and slash sections at the cat outlets. The plan is a part that will be a direct replacement. I also plan on a second Y pipe that will replace the center muffler section and bolt in and use the stock rear mufflers. These parts will give a number of options for power and noise levels. I will build them to suit my taste for relatively quiet operation, preserving low end power/torque and allowing peak possible power/torque.
Depending on how hard this project turns out to be I may consider making other copies.
Stay tuned.
