hog, thanks alot for the informative post. do you suggest I do the cats just like in this picture? I mean there is absolutely no way (the way i see it) to get equal lengh pipes before they hit an h-pipe or x-pipe.

Also, if I end up doing this, should I stagger the mufflers or could the mufflers be placed at the same location on both pipes?

Last but not least, whats the best location to place the cats, not for the sake of emissions but performance wise by acting as a termination for the collector length tune?

 

Am I the only one that saw this? lol

 

Nope i saw it too
seems like the tune is off and airflow could be adjusted to fix the starting issue

 

true, startup airflow and/or airflow final minimum would have solved the issue, you know thats true since my car is running the 87mm throttle on a 427.

 

1) If your headpipes and header collectors are the same diameter I suggest that you stagger the cats similar to the pictures.

2) So far as muffler placement, its best to place them as far back as possible. If you get them far enough away their role in actual exhaust tuning is minimized allowing you to place them in a non-staggered position.

3) For emissions the ideal place for a cat is as close to the cylinder as posible for a quick light off.
For performance, you can take a wax crayon and run it along your headpipes. The point at which the crayon is burned off (before the area where the crayon mark remains)is where you place the H-pipe.
I did some more research on collector termination and if the cats effective internal volume is close to the pipe diameter that cats can be placed right at the ends of the collectors and not affect pulse tuning in a major way.(the small bullet cats would be an example). If you use a cat with a larger volume, this will end up being your collector termination point.

This post has some great reading.(PECOS posts specifically)
GM Performance :: View topic - Started Long-Tube install...

Hope this helps.

peace
Hog