Test pipe Vs Chip

[Jmaak]

Okay so it is my understanding that the test pipe provides a large gain downlow, but nothing really up top. My question is, if i get chipped will the test pipe provide additional gains on top of the gains from the chip? Or will the chip negate the effects of the test pipe??? Thanks

[Phrost]

If you're completely stock, a chip will be a more noticeable difference.

If you already are chipped, a test pipe will make it a little noticeably faster, but not a whole bunch. It is definitely worth it to buy a test pipe. It's not like once you chip a TP is worthless or anything... Plus, you do have to remember to get the TP program (to delete the CEL) but you will also be stage 2 since it's a major exhaust mod.

[AlexK]

I went from TP + stock software, to TP + APR 93, to APR 93 + stock cat. I felt the most significant difference when I got chipped. The difference when I got the stock cat back in was noticeable but not too significant. The car felt slightly less punchy down low.

[Sly Raskal]

forgive the newb question, but what exactly does the Test Pipe do? Is it just like a header? Is it a legal mod?

[Phrost]

A TP (test pipe) is a straight pipe that replaces the catalytic converter. You unbolt your 1.5' cat, and bolt up the simple test pipe. It is illegal in all 50 states, and you won't pass emissions anywhere. It's is okay for offroad use (racing) though.

Header --> Turbo --> Downpipe --> Catalytic Converter --> catback exhaust.

The B7 A4's catalytic converter is bolted directly to the turbo, so I don't think we necessarily have a "downpipe".

[Sly Raskal]

^^^ I figured it was something like that but didn't want to assume without asking.

Can't the cops impound your car if they catch you driving around without a cat?

[Phrost]

I went from TP + stock software, to TP + APR 93, to APR 93 + stock cat.

So you went from chipped + TP then took your test pipe off to put the stock cat back on? Or was that a typo?

[Phrost]

Can't the cops impound your car if they catch you driving around without a cat?

I don't think they can tow/impound your car, but it may vary from state to state. I don't think police practice any method of "testing" to see if your catalytic converter is still good, the only thing they have is annual emissions testing if your area has it.

I guess all they would do is tell you to get it fixed... or fine you worst case scenario. I haven't heard of anyone having their test pipe "seen" and gotten in trouble from it.

It is illegal, but thousands of people drive around with blown out oem catalytic converters every day. Normal people would get a CEL from their cat going back and then get it replaced, but many people drive around with a CEL and shitty fuel economy and never get their car looked at. I guess it may be a different case if you purposely remove your catalytic converter, but I haven't heard any stories yet.

[Louis J.]

I went from TP + stock software, to TP + APR 93, to APR 93 + stock cat. I felt the most significant difference when I got chipped. The difference when I got the stock cat back in was noticeable but not too significant. The car felt slightly less punchy down low.

In other words, if you're gonna spend the $$$ on sofware, you don't really need the TP? I've got a cat bypass on my current car and the smell drives my wife crazy.

[Phrost]

If you are just chipped, you will still get gains from a test pipe.

Yes it does smell. It smells like every POS car you see on the road, because their cats are bad too and their owners don't care about their cars to replace them. Point being the smell is different but it is not that bad. I kind of like it because it smells like a drag car lol

It makes your exhaust note noticeably louder too at WOT.

[gsxtasee]

In general, Intake and Exhaust mods tend to be more understandable as providing in % of power made by the engine. as you start to bump up the output of the engine, the gain seen by adding a mod in these areas will increase (to a point). If you make 500hp and have a 2"exhaust (theoretically) you will see bigger # gains than a car making 200hp when adding a higher flowing exhaust.

As for the chip, you will see a bigger gain from it on a stock car than you would from an exhaust mod. Then when you modify the exhaust, you'll see another good-sized gain as it frees up the normal flow of gasses PLUS the increased output of gasses due to the chip & other mods you may have done.

were you to then take the car back to stock and dyno again, then add JUST the exhaust mod you added previously without chip or other mods, the increase in HP the exhaust mod gave you would decrease some amount.

I think I got a little more confusing in my explanation than i intended to.. but I hope you get the idea.

[gsxtasee]

^^^ I figured it was something like that but didn't want to assume without asking.

Can't the cops impound your car if they catch you driving around without a cat?

In CA I think they can impound you for Cat removal. I advise using a fake cat (test pipe with heat shields welded on) for CA street use if you intend to street drive a car w/o a cat.

[Phrost]

^ You could probably take off your oem cat and gut it if your state is that strict. My state doesn't do any emissions or anything, so I'm not worried about it...

[gsxtasee]

^ You could probably take off your oem cat and gut it if your state is that strict. My state doesn't do any emissions or anything, so I'm not worried about it...

Gutting a cat usually makes a bad idea as the turbulence from teh air going from small-big-small area is nearly as detrimental to flow as the cat itself. If you want to gut a cat you want to slide a straight piece of tubing in there (and weld in place in cat) to continue the flow path and thereby increase flow through the "cat"

[AlexK]

So you went from chipped + TP then took your test pipe off to put the stock cat back on? Or was that a typo?

Yep. I had enough of the drone w/ AWE exhaust and didn't feel too comfortable taking it to the dealer w/o cat.

[AlexK]

In other words, if you're gonna spend the $$$ on sofware, you don't really need the TP? I've got a cat bypass on my current car and the smell drives my wife crazy.

No, I'm not saying that. It was a noticeable difference in power with the TP on the car. So if you don't care about taking it to the dealer, increased noise, the environment, etc., you have no reason not to get it. Was it a huge difference? No, it was pretty subtle.

I liked the smell, I kinda miss it [=(].

[bhvrdr]

A TP (test pipe) is a straight pipe that replaces the catalytic converter. You unbolt your 1.5' cat, and bolt up the simple test pipe. It is illegal in all 50 states, and you won't pass emissions anywhere. It's is okay for offroad use (racing) though.

Header --> Turbo --> Downpipe --> Catalytic Converter --> catback exhaust.

The B7 A4's catalytic converter is bolted directly to the turbo, so I don't think we necessarily have a "downpipe".

Technically it is

manifold --> Turbo --> Catalytic ---> Downpipe ---> catback

You can purchase catbacks without the downpipe but most include the downpipe. There are some that do not include or even have one as an option.

cheers! Mike

[gsxtasee]

It seems like everyone is either ignorant of or forgetting about the option of adding a high-flow cat-con in place of stock cat or in line with DP-exhaust union. Best of both worlds. There are fewer environmental effects, a little less noise, high flow, deep sound.. etc. they usually run arouns $100-$200 last time I checked. I haven't had a cat on my Gvr4 in years so that pricing may be out of date.

[barkerd427]

Actually no one is forgetting that because they totally suck and they add very little if any power increases and one of them costs like $800. They've done studies.

[bhvrdr]

It seems like everyone is either ignorant of or forgetting about the option of adding a high-flow cat-con in place of stock cat or in line with DP-exhaust union. Best of both worlds. There are fewer environmental effects, a little less noise, high flow, deep sound.. etc. they usually run arouns $100-$200 last time I checked. I haven't had a cat on my Gvr4 in years so that pricing may be out of date.

If you want a quality high flow cat you know to get an HJS core unit that will still be efficient at only 200cpsi, not throw a cel, and usually not burn up. The cost is $900. HEre is an example of one...

http://www.mjbmotorsport.com/id81.html

OEM cat...

http://www.mjbmotorsport.com/sitebuildercontent/sitebuilderpictures/APR-NSExhaust-1-med.jpg

HJS 200cpsi high flow cat...

http://www.mjbmotorsport.com/sitebuildercontent/sitebuilderpictures/DynoNSMilltek-1.jpg

[barkerd427]

See the peak hp and torque are both lower, which you can probably assume they are pretty comparable due to variances. However, the OEM cat seems to have a more consistent power curve. It seems like a huge waste of $900 to me.

[tomasmdiego]

Is buying a eurocode test pipe and getting my cats removed and a pipe welded in by a muffler shop the same?

[Jmaak]

Sounds the same to me. The only thing is though you gotta find a place to put that o2 sensor.

[Phrost]

Is buying a eurocode test pipe and getting my cats removed and a pipe welded in by a muffler shop the same?

That is the same thing. However, there is a flange on each end and a bend that has to be pretty exact. There is also the hole with threads for the secondary o2 sensor. Not to mention that no shop will custom fab a bunch of crap welded together unless you do it after hours and you know the people [:)]

[AlexK]

If a HFC was close in price to a test pipe I would almost certainly get one.

[tomasmdiego]

yeah i have the people who will do it and they said they could for $125 cash no receipt but i just wanted some advice before going ahead and doing so...thanks guys

[Phrost]

$125 fabricated and installed is an awesome deal, so long as it is quality work and they do it right.

Test pipes you buy fit perfect, will not rust, and have a perfect threaded insert for the secondary o2 sensor.

Go for it if you can trust them (meaning you are friends with them) and make sure you either see what they are doing, or else look very carefully at what they did when they're done.

[PutTogether]

I would get the test pipe on first. It takes a few days for the CEL to come on, THEN you get chipped and CEL goes away. (Your car is way faster too)

[a2gtinut]

I wonder who is the i... who wanted gutted Milltek cat. He is from NYc area.

[ed@mtl]

I had the test pipe as well. After awhile, I couldn't stand the noise and some drone. Sold it.