My exhaust system seems to be making a clanking rattling sound which is coming from the engine compartment area, like a loose piece tapping on metal. Not sure where it's coming from.

I am considering modifying my exhaust to a 2 1/2" cat back system to hopefully clear up the issue and improve performance.

I would be interested to learn from members that have performed an exhaust modification if performance has improved?
Has your mileage per gallon increased?
Did it alleviate any rattling noises?
What type muffler (if any) and tail pipe kit was used?
Was the cat removed?
Would you have done it differently?

From a newbie trying to make this vehicle better.

Thank you in advance

IMO, don't waste your money on the catback system, unless you absolutely must have shiny exhaust piping underneath your CRD. If you want to do something to the exhaust, you should either 1) replace the muffler with a piece of 2.5" pipe or 2) replace the muffler with a Magnaflow (part #12226). The Magnaflow + install should cost < $100.

Whatever you do, make sure you remove the downsizing flange between the cat and the muffler.

Benefits: slightly better mpg, better coasting ability (improved mpg depends mainly on if you can take advantage of the improved coasting). The CRD will sound a little meaner, but no louder.

Others will disagree, but I recommend leaving the cat alone. It is very effective in cleaning your exhaust, substitutes for a muffler, and gutting it will give you very little if any performance gain.

linewarbr, could you tell me what model number exhaust and tail pipe you used?

I am considering going with a magnaflow just not sure which is the better one.

Must the rear tail pipes be replaced also and if so what is the manufacturers name and part numbers.

Pshh, I'll go you one better

Not only will I start coasting as soon as I see a light change in front of me (sometimes as much as 1000 feet) but here in Virginia, I'm coasting down every single hill. Gotta love it!

Right now, I think it is the only thing keeping my mileage at anything decent. I'm waiting for the boost solenoid to arrive, but typically I can fill the tank right to the top of the neck, and it will go just about 100 miles before the needle moves off of full.

This last tank I noticed it... I've gone just about 100 miles now since filling up... And the needle is below 3/4, heading toward 5/8. YUCK. I've also noticed recently that my EGT has been almost glued to 1000 degrees when I'm doing 65/70mph steady, where before just a couple weeks ago it was around 700. I also recall a couple months back, that when not towing, at the same speeds the EGT was at 600.

So something is definitely getting worse. I'm pretty certain that it isn't the solenoid not functioning, but it isn't able to make a good seal and is letting the vacuum escape, so the turbo can't hold high boost.

At least thats what I hope is the situation. If not... I'm out of ideas, and it isn't tossing any codes. (of course)