Terry Burger

I'm looking to improve my exhaust but I want to keep that stock look. Has anyone visually checked the stock Z06 setup vs. the stock C5 setup?

MattG

I believe a higher flow exhaust manifold was part of the extra 5hp that GM gave the C5 in 2001. So yes, 2001+ exhaust manifolds are a bit higher flowing. I am not sure of their physical differences though as I have never really paid that close of attention to exhaust manifolds! :D

Godspeed

Z06 manifolds are the equivalent of shorty headers on an LS1. The newer years also have (2) cats - leaving off the pup cats. I have a set off my 03 Z06 if you are interested...

niphilli2

As said above, they are quite a bit better. I would think you could pick up a set and do a little port cleanup to get a healthy gain on a '99

Greg_E

Yes, the 2002 cast iron exhaust manifolds are better than the "99's SS tubes. The 2002 Cats also flow better than than those used on the '99 and definitely are better than the systems that had the pup cats (some 2000 and 2001's). There are some issues that you will need to resolve. The dipstick and tube are different and one of the forum members that was looking into this, said the oil pan also was different. I have a LS1 in my basement, that has the cast iron manifolds on it and the dipstick and tube definitely won't fit. I don't know what is different with the pan.

Scubanme

I have a set of BBK shorty ceramic coated headers, Z06 cast iron exhaust
manifolds and stock 99 manifolds sitting side by side in my garage. I have checked them out carefully and noticed that the 99 manifolds are dual walled sheetmetal for heat control. The 99s are basic manifolds with a sharp 90 degree bend on the short side radius which impedes flow. The short radius is very important to keep wide as possible. The newer Z06 heads have D-shaped exhaust ports to raise the floor of the short side radius . The sharp bend causes the exhaust to cavitate and cause turbulence. The Z06 cast manifolds come with a external heat shield. They are "almost" like shorty headers. They do have
somewhat of short tubes, but only abut 2/3 rds the length of short tube headers. The Z06 manifolds have a 4 to 2 into 1 setup. The Z06 setup is approximately 1 inch shorter than the 99 manifolds, therefore requiring you to swap H-pipes if you decide to go the Z06 route. The shorty headers will out
flow the Z06 manifolds for sure, but the gains are only about 7 to 10 hp depending on mods. for the trouble, I would go to LTs. The air tube location and dipstick location on the Z06 manifolds Vs the 99s make the swap all the more difficult and you need to use Z06 exhaust gaskets. If you decide to do a header swap, then go with GM metal shim gaskets as they do a better job
of sealing uneven surfaces as compared to the composite gaskets. This is just my opinon and observation. :flag


[Modified by Scubanme, 8:13 PM 10/15/2003]