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Discussion Starter · #1 ·
I bought a set of used MP headers & am curious how tough an install they are for a 98 D? I'm also going to redo the whole exhaust while I'm at it & need to know what size converter to buy- I need it to be compatible w/ the headers and a cat-back.

Along those lines, what type of cat-back is quietest? I'm running a Hooker on the TA & it is louder than expected.
 

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I put my mopar headers on about a month ago and it wasn't that bad of an install. I had JBA's before and i have to say the mopars are way easier to install then the JBA's. I had my whole exhaust off and headers and new Y pipe installed in about 4 hours. I have a 2000 Dak R/T and my cat was 2 1/2" i just deleted it and went with a single 3" system with a flowmaster super 40 muffler. I have to say i had an original 40 and there is way more power there with the super 40. All in all you shouldn't have any problems hooking it up.
 

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forgot to add to your cat back question. If you want something that sounds good but isn't obnoxously loud i would check into a gibson or magnaflow cat back. A buddy of mine has gibson on his 4.7 and it isn't too loud but sounds aggressive. Haven't ever heard magnaflow but alot of guys like it from what i read.
 

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Discussion Starter · #4 ·
A few more questions:

How about the Dynomax system sold at Summit ? It sells for $206.95 and is advertised as being a 3" pipe system. Jegs advertises this same part # as being a 2.5" pipe :confused: . The Dynomax PDF file says it is 3", so I guess Jegs is wrong. According to this, you can buy just the pipes & a different muffler. The diagram there looks like the inlet pipe is necked down, so I suspect the cat outlet is 2.5". I can get a good high flow cat on eBay for about $60. I don't want to order the wrong size parts. I noticed there is an O2 sensor before & after the cat on my D. Are there any high flow cats that have these bungs welded in or is this a "custom" job?

I probably need to get ambitious & roll under the truck again to see how to install the aftermarket cat and retain the O2 sensors.

Found a sound clip of the Dynomax Super Turbo on a 5.2L D here on their website.
 

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No they are both right. The inlet on the muffler is 2 1/2" and the exit is 3" cause the R/T's use a 3" tailpipe. At least my dak r/t did. The pipe between the cat and the muffler inlet was 2 1/2. If your going to replace the pipe between the cat and the muffler then ya you'll have to have the O2 bungs welded in or get an O2 sim from KRC and then you won't have to worry about that sensor. So i take it your looking at Dynomax exhaust. Those mufflers come stock on the R/T's. The R/T's usually use a dynomax muffler from what i've heard. Personally you might be better off to get a magnaflow. Might get some more power out of the magnaflow. but if you lookin at price then that dynomax might be the way to go. Just remember you get for what you pay for. So if your not spendin much don't expect much.
 

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Well i just read your profile are you puttin it on your 01 Durango R/T or the SLT? On your 01 you should have 3 cats on it. Two are right off the manifolds and one after the Y pipe. Might want to see about eliminating those precats. you'll free up some more hp at the same time but you'll need the dual o2 sim box to correct that.
 

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Discussion Starter · #7 · (Edited)
This is for the '98. Thanks for the pipe size info. I looked for a stock replacement online, but no vendors seem to list the Durango. I did find a listing for a '98 Dakota and it showed the inlet being 2.25" and the outlet being 2.5" with an overall length of 59". I found a place online that sells a high flow 2.25 in/out converter w/ 2 O2 bungs for $108.

If the MP Y pipe is 2.5", I can buy a 2.5" cat, and run the remainder 3". I'm not looking for max power, and like the way the R/T sounds, so the Dynomax should do the trick.
 

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check out the mopar header Y pipe cause mine had an exhaust flange on it. So you won't just be able to slip the converter over the y pipe you'll have to bolt it up. But it could of been different in 98. There is a different listing for the 98-99 than the 00. What i did was just get a hooker header collector and weld an exhaust pipe on the end of it.
 

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Discussion Starter · #9 ·
Measured the pipe before/after the cat, both are 2.5". It looks like an easy job to put in a high flow 2.5" unit there with some adapter sleeves. I should have the headers soon, and will post after they arrive.
 

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Discussion Starter · #10 · (Edited)
I need gaskets & bolts for my headers, found the Fel-Pro gaskets, what size are the bolts?

EDIT
The ARP catalog says all Mopar header bolts for these motors are 5/16 thread by .75" long.
 

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Discussion Starter · #11 ·
wykdrt said:
...What i did was just get a hooker header collector and weld an exhaust pipe on the end of it.
What size was the collector? 3" or 2.5"?
 

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Well i got the 3" one but i think thats for the pipe. You might want to get a 2 1/2" one if your running 2 1/2" pipe. The only thing is, is you'll have to weld it on unless you get the cat so it'll fit over it. The collector i got from hooker headers didn't slip over or in the 3" exhaust pipe i bought. So i would imagine that it would fit inside the cat.
 

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Discussion Starter · #13 ·
Headers came today, the collector is a 3". I'm going to try & run 3" system with a 3" cat inline. The headers have the front O2 port, and I can buy a 3" in/out cat with an O2 port (Catco 2517, $66.69).

Summit sells part # HOK-11032HKR, which is a pair of 3" flanged collectors that reduce down to a 3" pipe. I should be able to slip the cat on over this reducer and then fabricate a pipe from the cat to the muffler inlet, using the Dynomax 2.5-3" adapter as a template. Dynomax's website says the muffler is 3" in & out, and while I could use their kit for the muffler & tailpipe (WLK-17354 $206.95, consists of inlet, muffler, and tailpipe w/ clamps), it looks like I can save some $ by buying parts individually since I'm going to run a 3" system:
(Summit part numbers)
HOK-11032HKR reducers $24.95
CTO-2517 3" cat w/ O2 port $66.69
SUM-640030 3" pipe x 4' $13.95
WLK-55005 tailpipe $91.69
WLK-17793 muffler $65.88
Total: $263.16

Total w/o reducer, pipe, & cat: $157.57

I'm going to pickup some collector gaskets as well as a few clamps.

This should fly since the 17354 system uses the 17673 muffler ($116.69 vs. $65.88 for the similar sized 17793 :confused: ), which has 3" center inlet & outlets. The 17793 has the same case size with an offset inlet & center outlet, and is 3" longer. If you look at the 17354 diagram in the Dynomax link above, you can see the pipe into the muffler is offset. By using an offset inlet, I can run a straight pipe from the cat to the muffler.

I found this link for their super turbo muffler specs.

I should have this stuff pretty quick from Summit & thought I could avoid their oversize surcharge since I'm not buying a complete cat-back except that they hit you with it for the 4' exhaust pipe :) .
 

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ya just be careful with that pipe your running from the cat to the muffler. One thing that i noticed with my headers when i got the collector welded to the pipe, the Y pipe collector made the straight piece of pipe angle towards the driveshaft and i had to go down to the local muffler shop and have them bend it. Well thats why i did mine myself cause they screwed the damn thing up totally. Bent it to far and at the wrong angle. everytime i have a muffler shop do my exhaust they screw it up. Anyways just be ready to do some fabrication to that piece of pipe. I would suggest clamping the system together first then having someone weld it up for you.
 

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ya i hear ya about the shipping and all but i don't have to worry about it where i live. I live 30 minutes from summit racing :mullet: so i just go up there get what i need and come home. Its so nice but not a good thing. I always spend money when i'm in there.
 
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