ATP Automotive Graywerks 101212 Exhaust Manifold

Vehicle: 1998 Jeep TJ Wrangler 4.0LThe mani seems to be well constructed. Welds are nice, pipes/ports placement is accurate, and flange thickness is identical to OEM. However, it will not fit without modification to the intake and/or exhaust manifolds on a '98 TJ 4.0L. The intake heat shield casting interferes with the #6 exhaust pipe, so either the casting "ear" has to be removed, or the #6 pipe has to be hammered to clear the ear. Also, the #5 intake runner interferes with the #5 pipe, so the #5 pipe has to be hammered for both manis to sit flush against the head. I was not brave enough to grind the intake runner, and it didn't look like I could remove enough material for proper fit, anyway. Once initial fit is addressed and intake/exhaust are installed loose, several of the lower manifold mount bolts are difficult to access, and thus torque to spec, as pipes (esp. the #3 and #4 pipes) obscure the mount bolts. 9/16th crowfoot wrench and a 1 ft wobble extension highly recommended. Torquing with a crowfoot on a wobble in a confined area such that the wrench has to be reset on the bolt to make the next, small turn is tedious, time-consuming work.If you want a nice "header-style" mani at a reasonable price and don't mind the extra time, effort, and alterations required to make it fit (at least on a '98 TJ), this is a good choice. If you want a replacement that fits accurately and bolts up fast with no fuss, get the  Dorman OE Solutions 674-196 Exhaust Manifold

I will start by not judging anyone's experience and abilities like I read here but by sharing mine with whom might spend the time reading it. I have restored cars, worked on cars and do most of my own mechanic work but I am not a mechanic. This is a well built header for the price, that said I suggest if you buy them to first get a cardboard (same shipped box will work) big enough to lay the headers and intake manifold on top as if fitting to engine block. Then anything from the intake that touches the headers should be shaved with a grinder as much as you can and try for fit. It will save you lots of time and undoing like I had to do. Then before you tighten anything to specs do/place the steering pump and belt at the same time as you torque things down. It will make things fall in place easier as it was for me (again my experience as per my adaptations). Now the car breathes better, I feel the most benefit in low gears, as per all Jeeps I guess it has to do with my gear ratio and tire size setup which is 456 gears and 35"mud terrain tires. I did not get any fuel/mileage improvements. Before I installed the headers I did a complete tuneup and replaced just about every sensor on the 97 TJ with 105k miles as well as added a K&N air filter, these gave me better overall response, mileage and power return for the money. Good luck.

The original exhaust manifold was replaced by this one after fifteen years, this one lasted six years. By the time I had replaced it, seemingly most of the exhaust was exiting the cracks in the collector pipe (see photos). Undoubtedly, most of the sound was escaping under the hood. I couldn’t take it anymore so I replaced it again, this time with a seventy dollar version which included the stress-relieving bellows on the first and last cylinders... hopefully the new one lasts longer. What I did find out when swapping them was that this ATP Automotive Graywerks 101212 Exhaust Manifold positions the pipes so that it’s impossible to use sockets and extensions to access two of the four fasteners on the bottom side. I had to use a wrench and my arm stuck between the engine block and pipes... not fun. The alternate manifold I just bought doesn’t have this problem and I’m happy to say, that one allowed me to torque all eleven fasteners! Not this ATP version though. Hindsight being very clear, I would choose another brand because this “pricier” version did not offer much life, even with new engine mounts installed. Oh well, Live and learn.

I knew before purchase that modification would be required, but it did take a little more than I imagined. As stated by the other reviewer and a google search for this header under either name atp or apn, the #6 exhaust tube will not let the intake manifold seat correctly without the aid of a hammer. I started by sanding a few mm of aluminum off the intake where they made contact but could not take off enough without risk, so I wound up using force to smash down the #6 tube a few mm too. A ball point hammer hit by another hammer with the manifold on the ground worked well, but slowly.With the manifolds off, I used rags and throttle body cleaner to clean the block ports, and thoroughly cleaned the intake manifold before reinstall. While sanding the intake, I also sanded down the obstructions in intake tubes 2-5 around the fuel injector mount hole, which are sizably larger than 1 and 6. There is a review on a forum that details that process. With a combination of a clean intake manifold, this exhaust manifold and cleaning the carbon buildup, I noticed a much improved throttle response and better fuel economy as reported by scangauge. The exhaust tone through a flowmaster 40 series was more distinguished and throaty. I noticed available power beyond 2k rpm is impressive, with a nice difference at highway speeds. It should be noted that the stock manifold was cracked where the two branches meet, and the gasket leaked a little until the engine was warmed up; replacing a fine stock manifold would not yield as much.For the cost of this intake compared to the headers it copies, including the old banks design, it is a bargain price for a premium product. Stainless steel that bolts to the stock exhaust downpipe is a quality better than oem replacement/upgrade.Prior Mods:Cold Air IntakeK&N Universal FilterBored Throttle body to 60mm4.0 Firepower Ignition KitFlowmaster 40 Delta Flow