Dynomax Cat-Back & EV6 Injector Upgrade...

Just finished installing the Dynomax Cat-Back system #17340, from Summit Racing (with a $75 rebate, why not!?) along with (not brand new) EV6 4-hole injectors, part #0280155784 from my local JY & eBay.

Fist impressions:
Cat-Back system sounds great, and the chrome tip adds a nice touch to the rear, system is larger in diameter than stock too.

0280155784 injectors:
Don't expect 13's in the 1/4 but your XJ "will definitely" idle better. Pick-up is crisp, and on point compared to previously. Engine idles "very quiet", sitting inside can't tell it's running. Before swap idle was rough; the tach never stopped jumping. Now tach stays put! Haven't taken it out to really see performance at highway speeds yet but will update once I do.
Prior to these upgrades, and Seafoaming the entire system, I would get approx. 14-16 mpg around Baltimore, now I'm curious to see what improvements in mpg I'll get.
A few things about installation that I encountered, that may be of help to you.

For the Cat-Back exhaust system you will need (2) 10 x 1.5mm bolts and lock washers! They do not come with the exhaust system!

These bolts are used to attach the adaptor to the cat. I had to use a torch to heat up my bolts they were rusted on so tight! The hardest part was removing those two bolts holding the adapter to the cat. I didn't have a sawzall so I had to use a hack saw and a lot of determination lying on my back to cut the hangers off to make removal easier. I cut the rear round clamp off; it wraps around the tail pipe next to the leaf spring. I did remove the bolt on the bottom but the clamp was so rusted around the pipe it would not budge, so I hacked it off. Next I hacked off the metal hanger behind the muffler a few inches below the rubber shock hanging from the body. WD-40 will make getting the hacked off piece to slide thru the rubber hanger easier. From here it was smooth sailing.
Total time for removal & install: 1.5 hrs.

The injector upgrade:
Before you start remove the gas cap & the fuel pump fuse under the hood. I think it may be fuse #19, I'm not exactly sure so you may want to check for your model year.
I forgot to do this and had a flood of gas pour out of the fuel rail even after I relieved the pressure using the pressure relief valve. Now start the engine; it will run for maybe 30 seconds then die, now you have no pressure or fuel in the fuel rail. Now disconnect the positive battery cable, and your ready to start.
I'm not going thru the entire procedure here because if you do a search for it here, and on other forums, you can find all the information you'll ever need to know on how to do this upgrade, I did. I'm just going over what issues I came across. Everything was straight forward, unhook cables from throttle body, remove bolts holding fuel rail in place, un-clip injectors, carefully remove fuel rail and injectors making sure no o-rings are left behind, then do everything in reverse. Don't forget to apply a small coat of oil to each o-ring before you install them.
One issue I had was getting the injectors back into the fuel rail. Yours may be easier than what I encountered but I had a small fight with them. The o-rings seemed larger, and would not go into the fuel rail, easily. I had to use a pocket screwdriver to carefully and gently finesse the o-ring into the fuel rail until it popped into place. Once figured out it was smooth sailing. Install the injectors into the fuel rail first, because they just drop into place in the manifold. Now just reconnect and reattach everything. Don't forget to reset your ECM!
Total time for removal & install: 2 hrs.

Conclusion:
I could immediately tell the difference when I took a small ride after these upgrades, and I'm extremely pleased so far. Biggest change was how it idles, very, very smooth. I'm going to filler up, and see how much my gas mileage will improve, I'll be updating as I see changes.
All-in-all easy upgrades; anyone can do it.

Total cost: $227.00
1-Dynomax 17340 system: $155 total with shipping from Summit Racing
4-Junkyard injectors: $36
4-eBay injectors: $21
12-O-rings, part #2-12093, from Napa: $13
2-10 x 1.5mm bolts & lock washers from Napa: $2
After I receive the $75 rebate from Dynomax total cost will drop to $152.
3.5 hours for installation, and a better running Cherokee....Priceless!
~Cheers