nj56gmc'
This article in Super Chevy presents a different point of view, describing the horsepower and torque gains from properly sized headers at street RPM as "amazing":
http://www.superchevy.com/how-to/49178-headers-power-increase/The article says in part:
"Look closely at the two torque curves and you will see a spike of 53 lb-ft of torque at 3,400 rpm while the 3,200-rpm line reveals a torque increase of 26 lb-ft of torque. These are amazing numbers that average more than 26 lb-ft of torque between 3,000 and 3,800 rpm. "
It also helps to know that spark plugs in the same heat range are available in a variety of lengths. These shorter spark plugs are in common use as original equipment on many vehicles and have the benefit of keeping the plug boots and wires farther from the headers. On the 350 sbc engine in my '32 Ford roadster street rod I've had the same spark plug wires installed since 2003 and in about 22,000 miles of driving with headers there have been no issues with cooked wires/boots, header leaks, or any other problems.
As stated by others headers are "eye candy" in addition to the other benefits, especially the stainless headers that turn a very light straw yellow from exhaust heat. Tastes obviously vary but I appreciate "eye candy" whether of the human or automotive variety.
