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Downpipe

T

Teecraige

New member
After months of misfiring and horrible gas mileage I finally decided to address my p0420 and but a new cat. But I noticed for about the same price I can get a downpipe instead. I'm just confused on 2.5 or 3 inch. I emailed zzp and they said 2.5 would be perfect but I've read through a few forums that say otherwise. I have an 04 gp GTP completely stock. I plan to eventually make a cai and purchase a power log.

Also I plan installing the dp myself. It looks like a couple Bolts and a pipe is there anything that may complicate that? And will I need any other parts that don't come with it
 
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I think its a 3" on the gtps, and 2.5" on the gts. I put a 2.5 zzp downpipe on my 01.

There are two bolts where it bolts into the engine, and two under the car where it goes to the resonator. The two that were in the engine came out like butter with my impact gun and the right extensions. The other two had to be drilled out, and I messed the resonator flange up. I ended up getting a whole exhaust off a 2004, for 60$. I put the exhaust on my car, removed the dp from the exhaust and used the ZZP dp.

The 04 exhaust fit perfect, and i don't get a bad smell anymore like a bad cat.

If you heat the bolts up, soak with pb blaster, they may start coming off, but I would replace with new bolts, as those get VERY rusty. I broke both the heads off when I tried putting a breaker bar on them to break them free. I soaked mine for a week, and had a torch to heat the bolts up a good bit.

The DP on the exhaust came off fairly easy. I was able to get the right angle with my impact gun and heat them up, and they both came off, first one came right out, second one started to strip, then it finally came.
 
its all the same. why the 3 inch is a up grade, will go well with the plog.

if you need a cat you can get a high flow 3 inch cat for 50 shipped off ebay. likely cheaper then zzp catted dp.

then theres speed daddy, they have 3 inch down pipes as well.
 
I have a 3" cat for sale, perfectly fine condition I just went with the cheater cat that looks legit, but I still have the high flow one sitting. I would sell it for $20 you pay shipping and paypal fees.... Hahaha
 


Mirraco said:
I think its a 3" on the gtps, and 2.5" on the gts. I put a 2.5 zzp downpipe on my 01.

There are two bolts where it bolts into the engine, and two under the car where it goes to the resonator. The two that were in the engine came out like butter with my impact gun and the right extensions. The other two had to be drilled out, and I messed the resonator flange up. I ended up getting a whole exhaust off a 2004, for 60$. I put the exhaust on my car, removed the dp from the exhaust and used the ZZP dp.

The 04 exhaust fit perfect, and i don't get a bad smell anymore like a bad cat.

If you heat the bolts up, soak with pb blaster, they may start coming off, but I would replace with new bolts, as those get VERY rusty. I broke both the heads off when I tried putting a breaker bar on them to break them free. I soaked mine for a week, and had a torch to heat the bolts up a good bit.

The DP on the exhaust came off fairly easy. I was able to get the right angle with my impact gun and heat them up, and they both came off, first one came right out, second one started to strip, then it finally came.
Click to expand...

Thanks...I guess should soaking those bolts in oil now
 
The resonator flange bolts might not break if you can use a torch to heat the flange. In my experience, one will snap off. You can drill that out and use a bolt and nut, no worries. The front ones might back out a stud but thats OK. If you buy a zzp DP, they can come with proper gaskets depending what you order. I have their 2.5" dp on my 99 GTP with no complaints but use a rear 02 emulator. I got mine so I'd have a new flex joint, cat, and u-bend delete all in one. The only thing to swap over is the O2 sensor.
 
My opinion but the 2.5 DP with plog is good if you are only doing minor bolt-ons with no future upgrades. If you plan on doing further mods I would recommend skipping the dp and running headers. $200 Speed Daddys on Ebay.

On my 04 GT when I replaced the catback I used an air rachet on the bolts between the resonator and DP. They were very rusty and they just stripped. Grabbed a grinder, zipped the head off, and knocked them out. Very rusty. I had new ones ready so be expected for them to break, rusted solid, and fight you. I tried to torch them with oxy/acl to loosen but they were too rusted to come out. Just stripped out.
 


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