[JohnF]

I am by no means an expert but I have been playing with different set-ups on my Z/28 for almost 24 years. Here is what has worked for me. I run 72 jets on the primary side and 76 secondary side; yellow secondary spring and 25 squirter. Headers do make a difference! I currently run the 1 3/4" Hooker Super Comps, 2 1/4" pipe to a cross flow muffler, and 2" tail pipes. The only muffler, other than stock, that performs better (and is not too loud) is a DynoMax cross flow that is listed for the Buick GN. It is a bit shorter than stock but looks good under the car and seems to flow quite well. As far as timing advance, I run 10 to 12 initial and 36 total, all in by about 2200 rpm. I have never felt that going over 38 did much to create any more power. These are not racing modifications but work very well for me on the street. I have tried everything over the years including the original manifolds, etc. With the quick timing advance you will need good gas. You may want to visit the Camaro.net site and do a search under the name JohnZ. He has studied the original 30/30 cam and gives very detailed instructions on how it should be adjusted. Again, just my opinion, but this works very well on the street.