delete only one pre-cat...
Thread Starter
Junior Member
Joined: Jun 2016
Posts: 4
Likes: 0
delete only one pre-cat...
I got a 1999 f150 4.2 and I had to remove the driver side pre-cat (rust hole). now the pre-cat on passenger side is still ok. Do i need to remove it too so the back pressure's equal on both side or I can just leave it as it is?
Thread Starter
Junior Member
Joined: Jun 2016
Posts: 4
Likes: 0
this diagram show the exact set-up... the part I'd removed is the one in front, driver side (just over the #4 on the picture)... ,maybe I'm wrong but I've read that it was a pre-cat...
Last edited by Franky Wood; Jun 20, 2016 at 12:50 AM.
98 F150 5.4L E40D/4R100
Joined: Nov 2006
Posts: 28,490
Likes: 7,619
From: MI
Yea, it's a false assumption made all the time. You have four converters, same set up as the V8's. The upstreams are more restrictive than the larger downstreams. I don't see nothing over #4, but the upstream is in front of 4.
Trending Topics
Senior Member
Joined: Jun 2016
Posts: 302
Likes: 28
I'm going to go ahead and subscribe to this thread. My truck has over 200k on it, and the stock manifolds are leaking, 4 studs are broken off, and mentally I'm not prepared to drill out the stock manifolds. I have a setup in mind, going to go with shorties, 2 cats, and 2 mufflers. Im going for depth vs volume, meaning I want a low, resonant sound vs loud and raspy. If anyone has suggestions, I would love to hear them. I really do appreciate everyone's input here on this forum!
I'm going to go ahead and subscribe to this thread. My truck has over 200k on it, and the stock manifolds are leaking, 4 studs are broken off, and mentally I'm not prepared to drill out the stock manifolds. I have a setup in mind, going to go with shorties, 2 cats, and 2 mufflers. Im going for depth vs volume, meaning I want a low, resonant sound vs loud and raspy. If anyone has suggestions, I would love to hear them. I really do appreciate everyone's input here on this forum!