Exhaust Modifications

[Thieleng]

I changed out the headers on my SPF/Roush 427IR, and also changed out the SPF packs with the Classic Chambered Cobra Packs. I followed with interest numerous discussions on the site where claims were made as to the changes in performance associated with these modifications. I wish I would have dyno'd the car before and after but I did not have the opportunity. The changes made a Huge difference in the performance of the car. The noise level is appreciably higher when accelerating but at normal cruise levels I find very little difference. A number of cars in my area are making the same modifications due to the performance changes witnessed in my SPF. Working with Classic Chambered and Reno Engine and Drivetrain (RED) was great and I highly recommend them. www.classicchambered.com

[Blas]

You have a PM

[RedBarchetta]

I'd be interested to learn more about your custom headers. Who did the work? Pics available (on and off the car)? What cylinder heads did you have them matched to?

Thanks,

-Dean #747

[jwoodard]

I did the same thing, changed headers and side pipes and was fortunate enough to have dynoed before and after. I went with polished stainless headers with 2" primary tubes and built my own side pipes using 2" primaries into a Hooker headers 4 into 1 collector and a Howe Racing muffler, part #H3002. Picked up 59 RWHP and 50 RWTQ with the change.

[dlang14]

Thieling,

Which model mufflers from classic chambered did you go with? I'm guessing 3" OD, but with or without packing? What length? Its taken me a while but I finally manged to get my hands on a set of the SPF 402 headers to match up better with the AFR heads on my Roush motor. I plan on doing the headers and sidepipes at the same time.

Thanks,

Daryl

[Thieleng]

The Roush motor has AFR heads, I purchased the 402 headers, the classic chambered mufflers are 3"OD, with packing. The headers that were on them was not matched well to the heads, when the headers were pulled off the carbon deposits were on the flanged edges of the pipe, in other words the pipe sizing was smaller than the exhaust opening. Stephen Bramlit at RED in Reno did the work on the car. I will try and get pictures but the pipes are out being powder coated as we speak.

[RedBarchetta]

I'm patient.

[Powershift1038]

Hey Dean, didn't you already do a muffler upgrade? If so.. did you feel a difference?

[RedBarchetta]

Yes I did. Went to 3" ID Stainless Specialties pipes. Didn't perform pre/post dyno, but definitely more power and more noise. You can't get one without the other...prepare for the trade-off. WOT is L-O-U-D.

-Dean

[Powershift1038]

Aaaah, the neighbors already hate me anyway. I ruined them with the Pantera when it was here. So, I guess that gives me a green light to make the Cobra louder. Ha ha!

[Got the Bug]

Daryl,

Where did you find the SPF 402 headers? I didn't see it offered as an option when I ordered my car. If it's an option, I'm guessing that it will take months to get from the factory.

Thanks,

Doug

[Thieleng]

I was able to get those through Dynamic Motorsports in Reno, Nevada. I am not sure but I think these headers (402) are what comes with the car now, could be wrong, the previous headers were more restrictive. Anyhow John at Dynamic or Stephen at R.E.D might be able to help you out more. I will try and get by their shop(s) tommorrow and ask them the question and will try to get back with you on the right answer to your question.

[496fe]

Just as I was reading this post, Dean blasted by on the street behind me. No probelm - I have duct tape for the windows.

Brian

[Thieleng]

Hmmmm...could be the reason that the car alarm went off on the Porsche in the garage when I pulled up the other day...I will live with the performance and turn a deaf ear to the noise

[Got the Bug]

Thieleng,

Thanks for the info. I need to touch base with with John this week to see how the cars coming along and also plan to talk to Stephen about some questions I have. Let me know what you find out about the headers.

[dlang14]

Doug, your car should come with the 402 headers, but it's worth double checking.

I got mine from Dynamic, but they are hard to get right now unless you buy a car to go with them. I lucked out and was able to get these from a guy that had planned on a 351, but then changed his mind in favor of a 302.

Daryl

[RedBarchetta]

Originally Posted by 496fe

Just as I was reading this post, Dean blasted by on the street behind me. No probelm - I have duct tape for the windows.

Brian

Sorry I couldn't swing by to say hello. Well...the romp in 2nd gear was my hello!

[greg schroeder]

On my engine the Superformance small block headers covered right about .3 inches of width coming off a Roush 427R with AFR 205 Heads. This made the exhaust surface area reduced by aproximentally two exhaust ports. It's probably not a big deal under 4500 RPM, but what's the point in buying a hot engine and pluging it up.

I put on a set of 2" unequal lenght primary headers from the Olthoffs that don't cover the exhaust ports. I got Buckshot Racefab side pipes.

I went to the drags recently with DA of 1480 ft. The track had terrible traction, but the Roush 427R trapped 130.33 mph.

[496fe]

Sorry I couldn't swing by to say hello. Well...the romp in 2nd gear was my hello!

Just for the record, I know your car only does 38 MPH in second. You might want to think about changing that 7.78 rear end.

[Thieleng]

I checked my information on the 402 headers, these headers are coming on the newer cars, I bought my car about a year ago that had the reduced size associated with the headers. I was able to get mine through a swap and I believe that they have some on order.