stevebez

Well finally had the car exhaust properly done and with the secondary cats gone (Kleemann headers <-> oem resonator) the sound is noticeable in that it is much louder at full throttle and just off idle but no drone at freeway cruising speeds. Result! Finally sounds like a 600hp+ monster!

Sorry no pics but have not been able to get under the car properly yet.

OEM resonator remains in place with oem fittings so I can swap back to cat section if required .

Anyhow it may be complete placebo but car definitely feels more "alert" and feels faster ... I really cant say for sure but that's the sensation and Ill take that.

I've NOT gone for a balance/kiss pipe ... any thoughts on this from a performance perspective ?

AKnight55

I noticed a nice but dyno gain in the 2-3k range.. Sound much more like an AMG should sound too..

stevebez

Yes exactly bump at 2-3k, it really is quite obvious when it hits...

And agreed on the sound !

Celicasaur

So was this a 2nd cat delete WITH Kleeman headers on the same day, or did you have them previously and you only just took out the cats? I might do this too then...

stevebez

Had headers done some time ago and did a bit of a botch when fitting them to the oem midsection. I was going to redo this and thought well no need just put straight through pipes in between kleemanns and the resonator and leave the oem section that I had done for testing.

Think its decent almost plug and play setup now between test version and "on the road". I was reluctant to delete the mid cats for emissions regs etc but I am really surprised at the but dyno and the change in sound .. was most welcome.

Toadster

"Is an "X" pipe better than and "H" pipe? - from Flowmaster website

Not necessarily. Flowmaster has performed extensive dyno testing of traditional “H” pipes and various “X” pipe designs and has found that in most typical street applications, there are no clear benefits of one over the other. “X” pipes have become a buzz word in the world of performance exhaust, and are now produced in a wide variety of styles and designs. Some types perform well, and some others can be quite bad due to the excessive turbulence generated in the merge area. Unlike anything else available, Flowmasters Scavenger X-Pipe design features patented D-port technology to maximize the communication surface area between the two banks of cylinders, and maintain the exhaust pulse velocity for peak scavenging. In terms of sound, an X-pipe will generally provide a smoother, higher pitched tone than that of a traditional “H” crossover pipe. In some specialized race applications such as small cubic inch engines and /or restricted (small bore) carburetors, we have found that an “X” pipe can respond well over an “H” pipe. As with all race applications, there is no substitute for time on the dyno, developing the engine package as a system."

here's an H-pipe vs X-pipe chart (from a Mustang site)


hardly any difference but the X-pipe will be quieter vs the h-pipe - either way - it's better than no cross-pipe altogether because it helps even out the pulse in the exhaust and helps with scavenging

SavMan

How have you dealt with CEL have you disabled the rear O2 sensors with Star?

I went a different route with primary and secondary removed and replaced with one set of 200 cell cats and an X pipe into OEM Resonator. I had the exhaust checked last week from the cat back and still found over 0.3 bar of back pressure which surprised me as most seem to suggest that the back pressure is mostly in the cats and headers.

stevebez

Second 02's deleted by Kleemann with the header install. The secondary cats are irrelevant wrt the 2nd O2's as they sniff after the primary cats.

I need to think about the H pipe a bit ... It seems the location of the pipe would be quite important to get the scavanging benefits? I'll keep car like this for a bit and see how I like it ... Spent way too much as it is...

That hp comparison is interesting .. I wonder how no H/X pipe would have fared? The link pipe just merges the gases slightly ahead of the resonator .. So I'm struggling to understand the physics here...

0.3 bar back pressure from resonator back I.e excluding the 200 cell cats? Ufff looks like more gains available then !

Btw I went for 3" tubing for mid section....

komp55

Don't forget that although its design and location are not optimal, there is in fact a crossover port in the factory resonator, so it's not like there is no crossover between cylinder banks at all.

munich55

Is there really so much different in sound?

AKnight55

From the secondary cat+ resonator delete, yes very much so over stock..

stevebez

Well I just got rid of 2nd cats and it's very noticeable. I think without the resonator it would not be pleasant on long trips.

Yep the resonator is effectively a link pipe but seems its main task is to eliminate drone. Seems a link pipe also helps in this regard but from what I have read can also add a bit of power while reducing noise. App it cannot compromise power ...

I quite like the sound now and will stick with it a whole longer and see how it goes ....

SavMan

Where did you get it done Steve?

stevebez

Fastroad conversions aka Powerspeed in Ashford. Only other chaps who could do this is Hayward & Scott, but they also not cheap!

They very busy and had the car a week but did a very clean job, although £720 worth Which is way more than I expected and was quoted.

Fair amount of piping + flexi's and app took a days labour to finalise...

stevebez

Hey SavMan where u get yre heads done? I was tempted by ricwood/cncheads, but at mom schools fees taking priority!

Celicasaur

For just deleting the secondary cats!?

SavMan

Torque Developments had the car at the time and agreed to design and complete the work around the same time as they finished my Skyline engine but they may have sub contracted it as they typically work on Jap cars. I will check with them as they have the car for the next couple of weeks designing a custom intake.

I have spoken with Hayward and Scott about a complete system including full length headers, as you say not cheap about 2 terms worth

stevebez

I am considering home schooling!

The cost was for new mid section, from kleemann headers to oem resonator, sans cats, with oem fittings.

munich55

I think about to reinstall my secondarys and delete the primarys for performance.
Would the make any difference in sound?

stevebez

So yre secondaries are gone but u got yre primaries?

I think deleting primary and refitting secondaries will make it quieter

munich55

Yes steve.
I removed the secondarys because i was afraid to get cel of the o2-sensors
but now i think i should remove the primarys and reinstall the secondarys to get the heat away of the enginebay.

stevebez

I would get rid of both if u can skirt the emissions.

If not, I agree I would chop primaries before I got rid of secondaries.

What headers u have?

munich55

That's impossible here in Germany :-(

But do you really think the sound would get quieter?

I have got some vrp-shorties but they are reweld so have to do something that they won't crack again.

grimm

What does your car sound like now? I've been debating going this route, but am afraid that hacking up the system would cause the car to sound like a tractor.

Do you have a way of recording a video and posting it by any chance? There are a lot of videos around with those with shorties, keeping their primaries but having gotten rid of their secondaries, but none (that I've come across) that show how the car sounds with the kleemann headers, secondary cat delete, oem resonator and oem muffler.

stevebez

Its really difficult to describe and document as on idle is sounds solid, on part throttle relatively quiet and when wot it wakes up pretty quickly. Cant really do a video of this.

I got no link pipe so its louder than those with a link pipe. It definitely does not sound like a tractor! Still refined on mild driving, but give it some and wham!

I dont drive the car much (not a DD) so I dont mind the louder pitch as it adds some occasion to the driving experience. Maybe if I used it as a DD I might fit a link pipe to tone it down a touch.

Ill try do a video if I can but not much one can do when car is stationary ...