Thorley Headers
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New User
Joined: Apr 2009
Posts: 6
Likes: 0
Havent installed mine yet, maybe next weekend. I just measured the right(pass.) side header from the cat flange face to the center of the rear header tube. Its approx 20 1/2" . Crawled under my truck (2000 excur. w/auto trans) and measured from cat flange to last exhaust port and it looks pretty darn close. The cat flange on mine is almost dead center of the trans pan. Hope this helps
Elder User
Joined: Feb 2007
Posts: 805
Likes: 1
From: South Bend, IN
Well that sucks... Now I gotta ask since I always considered it being a possibility... Will I be hurting anything if I just decide to cut out the cat and make a pipe from behind the cat to the flange of the header?
Postmaster
Joined: Jun 2008
Posts: 2,564
Likes: 11
From: Wayyy NoCal, USA
Yeah, it will stink (those of us who drove pre-cat cars/trucks know what I'm talking about....) and produce several times more noxious/hazardous emissions. May lower fuel economy. I believe it will also cause the CEL to stay lit up as the downstream O2 sensor will be seeing readings way out of whack.
Elder User
Joined: Feb 2007
Posts: 805
Likes: 1
From: South Bend, IN
Headers are on! Exhaust at idle is definitely quieter. Inside the cab it sounds like a rice burner. Outside on the throttle definitely seems louder. Seems like I'm getting better pedal feel and that power has been shifted throughout the RPMs instead of just higher. I did leave the cat on and I do have to take it back because the business I had put a pipe in to connect the header flange to the cat put in a bent *** crimped up POS pipe that looks like its more restrictive than the original y pipe. Overall I don't know if I'm completely happy about this mod but I am definitely glad to have finally gotten rid of that nasty manifold leak.
Next up is the 5 Star Tune and a Livewire Tuner from Mike. Hopefully I can get on that extremely soon and take full advantage of all my mods.
We don't have inspections here in Indiana. I understand the legal part of it but I was just curious if I was hurting anything by leaving it on or removing it. I've known for awhile that the stock exhaust was pretty decent as far as cat to tailpipe just the y pipe was pretty bad.
Next up is the 5 Star Tune and a Livewire Tuner from Mike. Hopefully I can get on that extremely soon and take full advantage of all my mods.
We don't have inspections here in Indiana. I understand the legal part of it but I was just curious if I was hurting anything by leaving it on or removing it. I've known for awhile that the stock exhaust was pretty decent as far as cat to tailpipe just the y pipe was pretty bad.
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Elder User
Joined: Feb 2007
Posts: 805
Likes: 1
From: South Bend, IN
About? The header being too short? No. I didn't figure they made a header specifically for the 99 that was longer. Although my mechanic did want me to contact them and tell them to change their bolts up a little bit lol. He said they were some of the worst exhaust bolts he's ever worked with lol.
Elder User
Joined: May 2003
Posts: 858
Likes: 1
Yeah just wondering if they new about it being short for the early models and offered a pipe. Not sure what you mean about the bolts. The guy that did my install said some of the bolt holes were off a little. On one hole he had to use an allen head because the hex wouldn't clear the pipe.
Elder User
Joined: Feb 2007
Posts: 805
Likes: 1
From: South Bend, IN
Maybe I'll try calling them tomorrow. He told me that the bolts seemed pretty low quality like some chinese stuff and that they should have made them 11mm instead of 12mm. Just little stuff that may have made the job easier.
Hotshot
Joined: Mar 2007
Posts: 10,101
Likes: 40
From: Pa
I'm shure Thorley is aware of the issues with the 99' Y. If I remember correctly Mizzitch (spelled wrong I think) installed thorleys on his 99' and ran into the issue with the y and a filler pipe had to be made.
My 04' has no egr and no O2 sensor after the cat. If you have an O2 after the cat removing the cat will set off the CEL. The rear O2 can be turned off with a tuner. I would just install and aftermarket "performance" cat rather than having no cat at all.
My 04' has no egr and no O2 sensor after the cat. If you have an O2 after the cat removing the cat will set off the CEL. The rear O2 can be turned off with a tuner. I would just install and aftermarket "performance" cat rather than having no cat at all.
Elder User
Joined: Feb 2007
Posts: 805
Likes: 1
From: South Bend, IN
Well... I took my truck somewhere else to have the filler pipe re-done since the shop that did it yesterday put un necessary bends in it and had it all crimped/pinched to hell. That shop will be seeing me soon with that POS pipe in hand demanding a refund.
Anyone else's sound like a damned import car inside the cab? I mean I understand why it would based on the way the motor works but it didn't before... why would it now?
I did leave the cat alone for the time being. I don't have an O2 after the cat so it wouldn't have been a big thing. Next up is a tuner hopefully next month or the month after.
Anyone else's sound like a damned import car inside the cab? I mean I understand why it would based on the way the motor works but it didn't before... why would it now?
I did leave the cat alone for the time being. I don't have an O2 after the cat so it wouldn't have been a big thing. Next up is a tuner hopefully next month or the month after.