240SX header 3" cat 80mm exhaust sounds like exhaust leak at 4.5k+?

[alkemyst]

I have a KA24DE with OBX header, random 3" cat, and the 5Zigen Pro Racer 80mm.

I am a little pissed the OBX came with a slotted flange for each bolt rather that a single hole on each side...my 3" cat is much bigger than the collector. I have backed the header flange to cat bolts with large washers.

At 4.5K+ or so it still sounds a bit more harsh than rumble...almost like an exhaust leak or V8 running dynomaxes.

Is this sort of normal sounding for a KA24DE?

I can't find an actual exhaust leak (no 'soot' on the flanges at all)...I'd really like to jack the car up and have someone rev the shit out of it, but at that point I may just drop it off at an exhaust shop and for $50-100 bux have them reweld two new flanges that are perfectly mated.

[240=180]

While your car is running hold a rag tightly over the tip of your muffler. If you have an exhaust leak it will hiss

[Matej]

It probably leaks through the slotted holes where the header meets the cat, especially if the gasket is slotted as well.
Go to an auto parts store and buy a stock gasket. The stock gaskets are actually 2.5" in diameter, which is the diameter of all aftermarket headers for the KA that I know of, so no worries, it won't restrict flow.
Also, make sure to use the biggest diameter bolts possible, I know that most headers/converters/exhausts usually come with bolts smaller than what you can fit in the holes.
Hope that helps a little.

[S14Cuhh]

how much for headers shipped to 90703

[alkemyst]

how much for headers shipped to 90703

dude fix your exhaust leak first.

[alkemyst]

It probably leaks through the slotted holes where the header meets the cat, especially if the gasket is slotted as well.
Go to an auto parts store and buy a stock gasket. The stock gaskets are actually 2.5" in diameter, which is the diameter of all aftermarket headers for the KA that I know of, so no worries, it won't restrict flow.
Also, make sure to use the biggest diameter bolts possible, I know that most headers/converters/exhausts usually come with bolts smaller than what you can fit in the holes.
Hope that helps a little.

that's not really help since that's what I am doing already. The problem is the 3" cat is about 1/4" of just gasket behind the bolts to the header.