Whistle in exhaust?

[krv94explorer]

I have a 94 xlt 4.0. Recently I have noticed a whistling noise coming from my exhaust. I first thougt the cat converter was clogged, but I took it to a shop & they did a "vacuum test" and it didnt seem to be clogged. I dont notice a lack in power but it annoys me!!

How do you drill out the cat? Will this help or hurt the performance/milage?

 

[NightHawk]

It sounds like you may have some small holes in the muffler. I would get a cat back system installed. They are fairly cheap and the performance and gas mileage gains will be well worth the expense. There are many quality systems out there, and they are really simple to install. You can do it yourself in your driveway in about an hour. Good luck!

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Happy Trails!
'93 XLT
4" Skyjacker (suspension)
3" Performance Acccessories (body)
31x10.50 BFG All Terrains (Till next week)
Dyno Max cat back exhaust
Rancho 5000 shocks
Poly bushing kit (front and rear)
More to come!