340 headers?

Actually that was a typo on my part. Should have read 40+ hp. The old FF (fat fingers)syndrome. I haven't every dyno'ed any but have read dyno reports online and in magazines that back this up. This is based on a 400+hp engine. My Desktop Dyno program shows the same thing. That's through the mufflers. Open headers show approx. 10-15 hp more.

BTW: Did you do any re-tuning after you installed your headers? If not you probably didn't realize the total benefits of them. Never owned a car with NOS but have riden in one. Since it is intantaneous it sure feels like a 500 hp rush even when it's only 125 hp whereas the headers spread out the power over a wider rpm range. Even then a 40 hp gain of headers can't compare to a 125+ hp gain of NOS.