Forward cat flange on an 88 2.9L

[norco98]

Hello There,

This is my first post here, but I have learned A TON from the site in general, so thanks alot to all of you posting technical info.

My question is simple: Have any of you modified the 3-bolt flange connecting the catalytic convertor to the forward exhaust pipes?

The reason I would like to know is because:

1. I have done a vaccum gauge check and there is significant back pressure. While I have rebuilt the engine last summer, I suspect the previous owner was damaging the cat by running rich or something along those lines. I can't take the cat off to inspect it visually because the bolts are (obviously) entirely corroded.

2. I plan on grinding the old cat off and replacing it with a less constrictive universal cat. (The direct fits are too expensive). The universal cats are sold with round inlets.

Any ideas (or a part number!) would be greatly appreciated.

Thanks again,


Jon

 

[Hahnsb2]

The previous owner of mine used a 2 1/2" pipe and ovaled it to fit and welded it in place, don't expect any power gain from an aftermarket cat though.

 

[UrbanRedneckKid]

heres mine, sorry bout the bad pic. I cut the flange off the cat, then split a section of 2.5 pipe down the side in like 6 places, bent them to fit the flange welded them up, then filled in the gaps with little triangle shaped pieces of steel, then welded up the whole thing. Also your gunna need to put some bends after the cat, because the factory cats aren't mounted in a straight line

 

[High Desert Ranger]

Napa part number EXH-15757 is a direct fit replacement for the front and rear cat. Pricey at $289