LS400 or Celsior Exhaust Mods

[Lextreme II]

Anyone modified their stock exhaust system on their LS400 or Celsior? I want to know about Noise and performance. I want to keep the quietness of the stock. This is what i have in mind, but my exhaust guy stated this will be very noise.

I am thinking about deleting the two primary mufflers/resonators and keep the two secondary mufflers. What do u think?

 

[INASNT]

I was thinking something similiar. Not loose the quietness when cruising but has a nice little v8 rumble when you give it some stick.

I wanted to just replace the rear mufflers with some nice magnaflow or lukey and put in some high flow cat as the stock cats smell like rotten egg everytime I give the car a bit of stick.

What have others done?

 

[JBrady]

David, the center mufflers/resonators do a lot of muffling and I suspect are more restrictive than average. The GS400 and all the 430 cars use straight through resonators in these locations. Your idea will work fine and if too loud you could add back some straight through resonators. Go with perforated wall not punched louver style if you do this. There is also some flow gains to be made in the Y section that splits the system back into duals.

 

[Lextreme II]

John,

Finally you are back. My current exhaust is pretty much like stock noise level. I have deleted the Y pipe, center resonator. Now all i have from the turbo is the two 2.25" pipes straight to the primary resonators/mufflers and the secondary mufflers. I was thinking deleting one resonator at a time and test out the noise level.

From deleting the Y pipe and replaced with dual 2.25" pipes, I dont noise any noise level increase at all. Perhaps the turbo is my biggest muffler.