Crow Horse

About 2 months ago I had a Performance Curve catback installed and I'm very pleased with it. The shop welded it in. Recently my downpipe developed a crack and will need replacement. The cat converter is original so I'll be replacing the cat as well as the downpipe. Any suggestions regarding the downpipe and cat? Performance Curve's direct fit cat is $220... Ouch!

Any experiences to share? Thanks.........

BlueRidgeMark

http://www.quadratec.com/products/51401_07_07.htm

http://www.quadratec.com/products/51410_1013_07.htm

If you want a "performance" cat you are going to be in the 200+ range. Waste of money, IMO.

BillyBoy

Thx for the links... I'm looking for the same.

Fred/N0AZZ

Unless you have a good "Stroker" engine I think the extra cost of a HP CAT is a waste of money.

Anony

Performance Curve's Direct Fit internals is the same as the (same manufacture) non-direct fit except for the O2 sensor bung and possibly the heat shield (as some cat's don't include a heat shield). My direct fit performance curve cat came with a 5 year / 50,000 mile warranty. Which at the time was $99.00 with free shipping. Current cost has gone up.

Universal cats such as from Walker, the o2 sensor bung is welded onto the cat's outlet pipe instead of the cat's body.

A few years after purchasing and installing one of Performance Curves direct fit Cat. My tail-pipe and muffler had rusted out, which have no warranties. However, the cat's heat shield had fallen off and the direct fit cat was replaced free of charge after sending them back the old cat converter with no heat shield. The warranty covers physical defects within the warranty period.

Non direct fit cat inlet and outlet ports should be the same size and length. (or nearly the same length as the direct fit) may or may not have an 02 sensor bung. Performance curve's direct fit cat, the O2 sensor bung is welded into the cat's main body, near the outlet whereas some universal's install the bung into the outlet pipe.


_________

Unless you need mandrel bent stainless I found Walker and similar work good as a front down pipe.

The tail-pipe, muffler and cat normally wear and rust out long before the front pipe.

I live in an area with high humidity and near the ocean where there's much salt and beach sand. After years my aftermarket non stainless and non mandrel bent front pipe is still in good shape. Since it's not stainless does have additional rust on the down section, where the crossover section is less rusted. One reason for this is the down section gets hotter (going from cold to hot) than the rest of the exhaust. Frequently going from cold to hot increases condensation, effects the metal, which in turn increases rust production. Mufflers sometimes do something similar by trapping hot exhaust gasses, increasing condensation.

The main difference is stainless potentially is able to last much longer steel, will rust on the exterior but won't decay. Steel exhaust, unless you live in a desert climate with low humidity, won't last nearly as long as stainless.

The factory's OEM front pipe, eventually was replaced because of an exhaust shop's repair prematurely failed. I was continually spending money on exhaust repairs, so I decided to start over using new exhaust parts. Probably should have gone stainless but opted for regular steel.

Stainless downpipes will also produce considerable rust, but will still last longer than most steel. ( Some of the oem stainless exhaust systems appear to have used a slightly thicker SS than what's available on today's aftermarket.)

I haven't really noticed any difference between mandrel and crimped. However mandrel bending exhaust is important for some because of performance issues and other reasons.

Another suggestion would be to repair the original stock front pipe which should be stainless. Performance curve should have the necessary parts for repair. You would need to be able to bend, fit and weld parts onto your old front down-pipe.

As for the cat I would just purchase a standard non direct fit cat. If a welded bung is not included you can weld one onto the outlet pipe or use a Fast Fit Pipeexhaust pipe with bung between the muffler and cat. An inexpensive exhaust pipe expander tool may be required to create a tight fit, which can either be welded or clamped.

http://performance-curve.com/225fastfitpipe.aspx

If you can afford it I would go stainless . Stainless will last much longer than steel exhaust.

Crow Horse

I did some searching and came up with Walker 55227 for the downpipe and Walker 15820 for the direct fit cat. Decent reviews but I'm concerned in that the pic of the downpipe has bungs for 2 O2 sensors (upstream, before the cat). The other concern is the lack of a "crimp" like the original has and if that will present problems because I'm at stock height....



Note the 2 O2 sensor bungs....??




Thanks for all the input. If these parts will work it'll set me back app. $180. Not too bad......

JeremyXJ

Magnaflow makes universal cats for under $100 and they'll flow better than most. In my experience, having the pre-cat pipe mandrel bent and installed at the shop won't cost much and it will also flow better than that wrinkled Walker pipe. You can either do it cheap, or do it right.

mschi772

Have a local shop fab you a downpipe. It won't be any more expensive than the one-and-only OEM replacement from Walker, and it will be higher quality. Heck, have them make it out of stainless, and it will still be pretty cheap.

Buy a simple spun cat from Performance-Curve for $60. Your mistake is that thinking you need a special "direct fit" cat.
http://performance-curve.com/425225.aspx


Dirt cheap and very high quality. Heck, at this point unless the Performance-Curve cat-back bundles have started including stainless, your new cat-back will now be the weakest link in your exhaust.



While my personal exhaust is NOT a budget exhaust, you can see just how cheap some of it is especially if you don't do stainless:

$500--304T stainless Thorley header
$100--409S stainless downpipe that a local shop fabbed for me (even has less extreme bends in it than factory for minimal improvements in flow).
$70 --409S stainless spun cat almost identical to the linked Thunderbolt (mine is by AP)
$120--409S stainless Flowmaster Super 50 Delta Flow muffler
$150--409S stainless tailpipe fabbed by local shop

The pipe is all compression-bent 2.25". It is better than crimped bends, and mandrel bending would have been nearly impossible for me to achieve, would have provided marginal benefit over compression, and would have cost SO much more.

Anony

My 98 has two o2 sensors, one upstream on the front pipe near the exhaust manifold the other downstream near the cat's output.

If the Walker front pipe has two o2 sensor bungs you can use a bung plug. Walker would probably include a plug if the front pipe has two different o2 sensor locations. AFAIK XJ's only use one o2 sensor upstream on the front pipe, unless the front pipe is a Y configuration connecting to a two piece manifold with the larger intake.

I seem to recall some XJ owners placing their upstream o2 sensor father downstream before the cat.

I purchased a direct fit cat and exhaust parts because I didn't want to do any cutting, fitting or welding. Took approx. ~30 min to install an entire new exhaust system using heavy duty clamps. All the direct fit exhaust parts were from the same manufacture so they had a tight fit and slid together fairly easy.

When exhaust parts are not from the same manufacture I sometimes use an exhaust pipe expander, so the different exhaust parts fit together fairly tight.