I sold Blacksambo a virtually new OEM exhaust ....

Quote Originally Posted by 89Vette View Post
I was talking to our Isuzu guru Jerry Lemond last summer, who mentioned the strong possibility that our mufflers have a warm-up valve inside. But he couldn't confirm it...nor could this forum.

If there were one...and it were stuck, it might explain an obstruction severe enough to cause a pronounced improvement.

???
....Maybe can cut up his old one...and check out the "valve" ??

Jo