TheNerfsmith Posted May 6 Posted May 6 I'm curious as to what you all have done in terms of the intake and exhaust. I have an 89 Renix and I've been mulling over in my head about what options I have for headers and a new intake. I'd like to return to OEM for the intake and remove the cold air intake currently in my MJ. The exhaust had to get repaired awhile ago when I first bought it and needs to get redone. So I'd like to hear opinions on different headers and exhausts if anyone is willing to share.
derf Posted May 6 Posted May 6 I'm staying stock on mine. Renix likely has fewer options than HO, but they are similar so I'm not sure how much croses over between them. I do have spare Renix intake and exhaust manifolds that look stock. They'll be available in the next couple of weeks.
JZLAJeep Posted May 6 Posted May 6 I've wondered if it's possible to use the two-piece exhaust manifold from late model XJ's. Would have to weld in a wye in the exhaust pipe where it connects to the exhaust manifolds, but seems like it could be done.
75sv1 Posted May 6 Posted May 6 1 hour ago, JZLAJeep said: I've wondered if it's possible to use the two-piece exhaust manifold from late model XJ's. Would have to weld in a wye in the exhaust pipe where it connects to the exhaust manifolds, but seems like it could be done. The two piece cast manifolds are for the smaller exhaust ports of the 0331 heads. There is about 1/16 'wall' if used on earlier heads. Not much sealing area. I think Pace Setter and possibly Clifford has headers for the RENIX. I did use a RENIX, and have a Cliford (bolted on, but not used).
JZLAJeep Posted May 7 Posted May 7 7 hours ago, 75sv1 said: The two piece cast manifolds are for the smaller exhaust ports of the 0331 heads. There is about 1/16 'wall' if used on earlier heads. Not much sealing area. I think Pace Setter and possibly Clifford has headers for the RENIX. I did use a RENIX, and have a Cliford (bolted on, but not used). Good to know! So not interchangeable I take it...
75sv1 Posted May 7 Posted May 7 7 hours ago, JZLAJeep said: Good to know! So not interchangeable I take it... I have not done it myself. I have had the manifolds, and put them on a '95 head. I doubt they last long, a start leaking very soon.
pizzaman09 Posted May 10 Posted May 10 My first MJ, a 1988 model 4.0L, had a Banks exhaust header. Not sure what specific model as I know Banks offers a few different ones. It was very nice, definitely made more power than stock. I have no idea how it was to fit up but my understanding is you can make them fit on a Renix engine given some massaging.
Kedosp Posted May 19 Posted May 19 I had to replace my entire exhaust system including the manifold when I bought my truck. I used a 91+ HO manifold and downpipe and blocked off the EGR port on the intake. The new downpipe also eliminated the restrictive oem dent in the renix downpipe. Getting rid of the egr cleaned up the engine bay a bit and it has to flow better now with the newer parts
hgeranium Posted May 19 Posted May 19 3 hours ago, Kedosp said: I had to replace my entire exhaust system including the manifold when I bought my truck. I used a 91+ HO manifold and downpipe and blocked off the EGR port on the intake. The new downpipe also eliminated the restrictive oem dent in the renix downpipe. Getting rid of the egr cleaned up the engine bay a bit and it has to flow better now with the newer parts That looks great!
JZLAJeep Posted May 19 Posted May 19 7 hours ago, Kedosp said: I had to replace my entire exhaust system including the manifold when I bought my truck. I used a 91+ HO manifold and downpipe and blocked off the EGR port on the intake. The new downpipe also eliminated the restrictive oem dent in the renix downpipe. Getting rid of the egr cleaned up the engine bay a bit and it has to flow better now with the newer parts Guess I hadn't realized the Renix and HO exhaust manifolds were so different, but now that you mention it...
TheNerfsmith Posted June 7 Author Posted June 7 On 5/19/2026 at 8:54 AM, Kedosp said: I had to replace my entire exhaust system including the manifold when I bought my truck. I used a 91+ HO manifold and downpipe and blocked off the EGR port on the intake. The new downpipe also eliminated the restrictive oem dent in the renix downpipe. Getting rid of the egr cleaned up the engine bay a bit and it has to flow better now with the newer parts Did you run into any issues running a renix intake or did you change that also?
Kedosp Posted June 12 Posted June 12 No issues other than needing a block off plate for the egr valve. They’re easily made, or bought for cheap.
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