i know most anything with longtubes especialy with a cam and longtubes will have that tinny scratchy sound where the flow hits the bottom of the headers. well my 5.3 hotcammed swaped 86 does this and im running 99 manifolds BUT i built a full 3in mandrel bent y pipe that follows the stock location and on the crossover under the tq converter i have one of those stainless woven flex pieces. ive got a few lil pin hole leaks back right before it goes over the axle where my cutout is but i have the car on jackstands and if you lay next to it while its running its up in the front and i dont feel any leaks. could this be the same sound effect? it kinda drives me nuts lol the magnaflow i put on it makes it sound stealthy except for the tinny sound up front that follows the cam lope. my 03 yukon xl with longtubes and ory on a stock 5.3 does this but i know thats because of the stainless longtubes.