Yes, it would be nice to know if the mods to the standard exhaust can be done without too much difficulty or cost (eg. at a local muffler joint if I supply the parts) as it looks like the TJW mod does not help with power gains. Richard has mentioned $1500 for the OEM modifications, which assuming is the cost of the 100 cell cats as well as the cost to bypass the original cats/retrofit the 100 cells.

More questions as well as the ones JB has asked about Richard's approach:

- Is this something that a local muffler shop can do?

- Do you have a DIY guide of how it was modified (and what was difficult)?

- Any ideas of the performance gains, especially compared to the better aftermarket exhausts? Are we 80% of the way here with this approach or is the OEM exhaust design still the main constraint (eg. poor flow, pipe size too restrictive)? I would assume the cats are the problem and Richards approach should have most of the gains.

- Would this approach be appropriate for people with a tuning goal of up to 600hp, so the real power junkies need to look elsewhere (and pay more)? ie. is this a cost effective approach for moderate tunes?

- Any more observations about the sound - assuming that removing & replacing the cats as well as the TJW mod will sound different to just the TJW mod alone?

 

DEADDOB: See my post #49....in this thread.....


The more I think, the more having a 100cell cat might just be good enough. If Ruf is happy, I suppose I could be happy.

Now, anyone out there know anything about cats and where to get them?

Jeff

 

I have a Fabspeed and the cats that come with it. I'm thinking maybe it would be an interesting project to use the Fabspeed cats with the factory exhaust. I got a killer deal on my Fabspeed, such that I wouldnt mind ditching the muffler and using the cats for this type of project.

 

I bought my 100 cell cats from FVD, I'll try and find the pics from 2003 on the whole operation but they should be either on here or rennlist if you search under my name

 

Not to be condescending, but have the two of you read the entire thread? Though the mod doesn't offer the weight loss that an aftermarket exhaust gives you, it does free up the flow and gave a noticable DYNO certified increase in power. Please go back and read the entire thread, I'm sure you will be quite impressed for such an inexpensive mod. It's not only for sound, even though that was the original intent of the modification. A few noticed that it seemed to have a side effect of giving more power. Then it was certified with dyno runs. Kinda like Viagara was originally designed to be a heart medication, however they found that it's side effects gave long lasting boners

 

Scott, you are right...but to be fair, Wooosh did hit a wall in power improvements at high RPM. That is "probably" the cat. Now , high HP at high RPM is probably the time and place for very high speed stuff, so perhaps not really important....BUT...cats out and in if cheap might give my TJW 2.25" mod (which is now probably 80% the to being as good as a decent aftermarket system) up to the level of an aftermarket system. RichardCH actually dumped two systems for his with cat changes and TJW. I actually like the sound a lot. More than a local guy's 3000$+ system. But sound is just taste. AND somehow, it just "tastes" better to spend $50 than $3000. EP is not lighter.....either. I suspect an FVD cat is the way to go...just ordered 2. We shall see....higher quality but heavier. I don't race the car for real...so for 99% of my time gains on the track it will be the carbon based life form that will need the most changes to get better times..... I just love to "beat the system"...if you will.

What TJW offers is the ability to avoid going into the baffles of the exhaust and just to do the primary cat (the one bolted closest to turbo). It should be "cheaper...." than what RichardCH and Ruf do...neither knew or chose to explore the TJW mod....RichardCH has been super happy per his posts.

On Viagra:

The guys that did the NO work got a Nobel prize, btw. The main science guy visited our lab in 2001 ...nice, down to earth guy...fwiw.

He was pretty happy at the side effect story....made for some cool slides and jokes....science nerd wise...

JB

 

fwiw I always had 0.1+ more boost with the modded OEM system (and never any cels) than either of my aftermarket systems, this mod just added the sound I always longed for

 

Richard...I found a thread with a dead link on this site and nothing on rennlist...

Please post pictures and...how many hours for the main cats would you guess?

Anyone have a guess....2-3?

TIA.

Jeff

 

To be honest not sure I have them anymore as that was before I had a full digital Camera in 2003. Essentially what we did was put the exhaust upright in a jig and used a grinder to split it on each side between the 200 and 400 cell cats. We drilled out the large rear 400 cell cats (you will save quite some weight here) and then from what I remember we used a mechanical press to push out the 200 cell front cats. We then used a mechanical saw to shorten the FVD 100 race cats, pressed them in and welded it all back to together in the jig to be truly honest its probably 3 hrs work on the exhaust per se and then +30 mins each to take the exhaust off and put it back on (but you need two people for this) so its not a small job. I had my upsolute stage 2 done at the same time, a very worthwhile day

 

I am assuming the big one after the turbo is a 400...could you take the attached JPEG and draw in the parts removed and the parts changed....to make it easier on me (and for when I go to my shop)....
Which is 200..which is 400... where to cut...etc.
THANKS!!!!!!!!

jeff

 

Here is the image. Orange is the TJW flow path. Thus, the medial stuff can be ignored I think.....chime in anyone who can help.

Thanks Richard.

Jeff

 

Let me root in my work email tomorrow may still have some pics there, the 200 cell cat is straight after the turbo, the exhaust then widens out for the second larger 400 cell cat after the 2nd Ob2 sensor (thats why removing the 400 cats gives you no check engine lights !) I would seriously guessimate just splitting the exhaust & drilling out the rear 400 cell cats would in itself produce big results and it ie 1/4 of the cost (no buying new cats) and 1/3 of the time that in itself is pretty easy of what I actually did.

 

Jeff,

Be sure to monitor this project closely...If this is not done in a jig with exact measurements, the exhaust will not hang properly and fitment will be a problem. You have to make sure you keep the exact factory measurements or you will have problems when you go to re-install it. If it is not done perfectly, it will put undue strain on the turbos/headers, etc., as well as, result in uneven tips at the end of it all.

Scott,

Of course I did...Sorry, but I don't buy it. The comparisons were done on two different days with different conditions and from what was described, the results were all over the place - just trying to get a baseline. With the dual cats in place, the exhaust is still so restrictive that IMHO, any power gains have to be miminmal. I believe it was also stated the peak power did not increase, but a few areas under the peak did. Personally, I think that the drilling of the hole is great if you are looking for sound, but if you want to maximize the performance of your car, you should be looking at properly designed exhausts with maximum performance inherent in the complete design.

 

Indeed John but saying that when I did the straight through sound mod and my precision Swiss engineer was first determined to drill it through rather than blow torch it, he whipped off both my exhaust outlets at source with a grinder to get better access, however subsequently put them back on as if nobody would ever know

 

John,

Will do...but I have played with the system and I think it could be trivial IF the following is the case



If there is a gap between the 400 cell and the 200 cell....then removing and or grinding the 400 out will do it enough for me.... I suspect making a window after the second 02 hole and going for it is all it will take now that the TJW is in. I don't have to "add" a cat at all...the 200 is in place. I would have though 400 first...but I guess we got lucky.


Here is the idea....Richard, please pipe in.


BTW, if you don't cut the casing completely apart, it is so stiff that I cannot imagine any problems down the road at all. Just me. Cutting from the part on the "upper" surface will be the smart way to go....more cosmetic from bellow later....wonder if there is a way to get the 400 out without changing the shell too much...


Richard, is there space between the cats?

So, this is what this dealer type was doing way back when....nothing is really new...