IMO, the second "Y" at the rear is restrictive. Take a peak at it, there's a crush where it splits and goes to the mufflers. Personally, I don't think the mufflers are a problem, and I like the sound. If you want to keep the secondary cats, why not build a real dual system that starts after the secondaries, and if you want more noise, leave off the resonators and replace the mufflers.
I wanted a dual system when I got my F, and I removed the secondary cats, but kept the stock mufflers. I did my exhaust mod when I had 100 miles on the car. I now have 7K miles, and am very happy with what I did. A thread outlining my changes is attached.
http://www.lexusf.com/forums/showthread.php?t=890
Lou
I wanted a dual system when I got my F, and I removed the secondary cats, but kept the stock mufflers. I did my exhaust mod when I had 100 miles on the car. I now have 7K miles, and am very happy with what I did. A thread outlining my changes is attached.
http://www.lexusf.com/forums/showthread.php?t=890
Lou