Stock Down pipes? Decat / Removal

[R3dn3k Flyby]

Originally Posted by Shepp80

Brilliant. Thanks for the info

Much power difference? Response?

While I didn't do a before and after dyno, I honestly didn't feel any difference in power. It does seem like I get slightly quicker spool with the gutted stock downpipes though.



Agreed with the rest of the comments above as well. If I were to do aftermarket downpipes again, I would definitely have them coated, but thus far, I honestly don't see the reason to do aftermarket downpipes on this particular platform. Some of the higher horsepower guys are still running gutted stock downpipes. Further, no one likes the sound of wastegate rattle, and that is pretty much unavoidable with an aftermarket catless downpipe. Makes the car sound cheap, and makes people who don't know much about cars assume something is wrong with your car everytime you coast down to a traffic light.

Also, as others have pointed out, if you ever need to go back to stock, you can easily purchased a used set of downpipes for roughly $300-$500.

-James

[mike@x-ph.com]

Originally Posted by DenverF10M5

Oh, so now you're going to pull THAT card? Two guys on here have disagreed with your logic, so you're going to resort to asking for test results? Come on Mike, think about the location of these downpipes. We're not installing downpipes on a 335 where they aren't located directly next to the block. The downpipes on the S63TU run directly behind the engine and within inches of the rear cylinders. Do you have tests that prove me wrong? No, you don't.

Wrapping or coating the downpipes is also going to keep that excess heat out of the engine bay, while slightly reducing heat soak. It will also retain heat in the exhaust. Hotter gas flow faster than cold gas.

This is all common sense. How about you do some tests yourself and prove my theory wrong. It makes more sense to wrap or coat the downpipes given their location. I can't imagine that heat doing anything to help the engine run more efficiently. Some of the more experienced owners can chime in, but I'm sure the top guys will agree that you will need to wrap or coat the downpipes. You're giving bad advice. I would stick to selling parts.

Im not pulling any card, i thought there were some tests done thats all.

[DenverF10M5]

Originally Posted by mike@x-ph.com

Im not pulling any card, i thought there were some tests done thats all.

To show you that temps are lower with coated downpipes?

[mike@x-ph.com]

Originally Posted by DenverF10M5

To show you that temps are lower with coated downpipes?

tests that show daily drivers will gain anything from coated downpipes whether it is performance increase or engine safety.

I was not being a smart ass when i asked for tests. it was a genuine question.

If it is a matter of opinion, in my opinion daily drivers dont have to get them coated. Of course your opinion is different and i respect that.

[nissan]

Originally Posted by DenverF10M5

You're still paying $200 more. I haven't read any reviews on fitment. Then you'll need to have them wrapped or coated due to the excessive heat.

Fitment is decent, but not perfect. Your shop will have to do some bending of the bracket to install it. Still, it's better than any other aftermarket pipe out in the market for $600. I'm happy w mine and did end up getting them wrapped bc why not? It doesn't add a material amount of time or cost to wrap them. Coating costs $150 w Swaintech and I would've gone that route, but time didn't allow for it.

[DenverF10M5]

Originally Posted by mike@x-ph.com

tests that show daily drivers will gain anything from coated downpipes whether it is performance increase or engine safety.

I was not being a smart ass when i asked for tests. it was a genuine question.

If it is a matter of opinion, in my opinion daily drivers dont have to get them coated. Of course your opinion is different and i respect that.

An M5 is a daily driver. Whether it's driven 2 times a week or 7 times a week, how does that affect the temperature generated by the downpipes?

You're referencing tests done on which platform? My comments are related directly to the F10 M5 and the specific location of these downpipes in relation to the rear cylinders. The test you read was probably done on a different vehicle where the downpipes aren't in a location where the heat could potentially cause damage to the engine over time.

[mike@x-ph.com]

Originally Posted by DenverF10M5

An M5 is a daily driver. Whether it's driven 2 times a week or 7 times a week, how does that affect the temperature generated by the downpipes?

You're referencing tests done on which platform? My comments are related directly to the F10 M5 and the specific location of these downpipes in relation to the rear cylinders. The test you read was probably done on a different vehicle where the downpipes aren't in a location where the heat could potentially cause damage to the engine over time.

Im not referring to any tests thats why i asked you if you have any tests.

Has there been any reported damages from non coated downpipes?

[DenverF10M5]

Originally Posted by mike@x-ph.com

Im not referring to any tests thats why i asked you if you have any tests.

Has there been any reported damages from non coated downpipes?

The excess heat has been blamed on a blown engine or two. It's been discussed in the forums a time or two. I think you're missing every point I've made to you. You don't think the excess heat will cause damage to the rear cylinders? Why did BMW engineer their downpipes to be double-walled?

[Earthmaster]

precisely why I just bought some OEM ones are gutting it.

[Bowser330]

The reason the stock is double walled is the catalytic converter which is made of ceramic material holds in a lot of heat as it uses the exhaust heat as part of the chemical reaction to turn noxious fumes from the exhaust a little bit less noxious.

Without the presence of a cat the heat will pass through the catless downpipe without obstruction and the pipe won't heat up nearly as much.

With increased power comes increased heat and with aftermarket tuning and racing there will definitely be increased heat. Due to the extra heat and the positioning of the downpipes to the engine i would be more cautious and get coated or wrapped for racing setups, maybe even extremely hot climate setups.

Makes no sense not too wrap the downpipe considering the low cost involved relative to any possible engine issue. Coming from a hot climate, I would wrap mines.

[Kisenwether]

Got a set of OEM for $350. Way cheaper and perfect fitment compared to aftermarket.