My experience with cat backs on my '94 was great sound and absolutely zero increace in performance. The exhaust restriction in the '94 is in the stock exhaust manifold.
The drag radials should help a bit in your 60' times and overall ET.
That said, if the weather is hot/humid, and the bp is low, you may not actually be able to qualify any increase in performance at the track. Weather can vary performance by several tenths.
Clean the air filter, make sure the plug wires are good, that you have good gas, and have fun. Don't worry too much about performance. Concentrate on your launch and reaction times.
------------------
'94 Black Z28, 383, 700R4
1/8 ET: 7.49
1/4 ET: 11.86
1/4 MPH: 112
http://www.downtime.cz28.com.index.html
__________________
'94 Black Z28, 383, 700R4
1999 Champion Oxford Dragway
2002 Champion New England Dragway
11.86 at 112
http://www.downtime.com