I'm looking at the Pypes 2.5" mandrel SCC12 system for my 69 427. I've done the search here and noted the numerous difficulties a number of guys have had getting it installed. The good news is that I have a friend who builds custom mandrel systems at a high end hot rod shop here in my town and he says the adjustments won't be a problem for him. He'll do the work on his own time at a friendly rate.

I'm sure he can get the header collectors mated to the front of the system. My concern is the back end where the pipes connect to the mufflers. I have Dynomax polished SS Ultraflos which I love the sound of, and I plan to keep those. They are offset inlet with centered outlet, whereas the Pypes mufflers are offset on both ends. I can see where this might affect the alignment slightly where the pipe meets the mufflers, and I don't want to have the tips pointing inboard or outboard as a result.

So here's my request- could somebody who has this system please measure the distance from the inner edge of one pipe to the inner edge of the other pipe, right where the pipes connect to the muffler inlet stub? That would tell me for sure if this system will work for me. I checked and Pypes doesn't have those dimensions.

By the way, for those who would tell me to go with a 3" mandrel system, I gave that a lot of thought and put a fair amount of research into it. Last week I talked to the biggest supplier and fabricator in my region. These guys are actually involved in gas flow research, so they have credibility. They could have made money off of me but they recommended me away from a 3" system for my power level and usage. They felt that for little or no gain the drone would probably end up at an RPM where the car was likely to spend too much time and I wouldn't be happy. Add to that the cost factor- my other half isn't exactly delighted even at the much reduced price of my current plan.

 

I have the SCC12 and used offset in, center out mufflers. They are longer than stock so the pypes system had to be modified.

As long as you have someone that can cut & weld it as needed, your muffler choice is not a problem.

As mentioned in other threads: Order a spare 1.5 ft section of 2.5 SS tubing to make it reach the headers.

The modification I did to mine ('71, 454, hooker 1 7/8" headers):

Lengthened front pipes to reach headers. Added 3"->2.5" flanged reducers (not incl w/ SCC12).

Cut front pipe bend to correct angle.

Bent the long center section w/ x-pipe to avoid rear pipes from hanging too low.

Cut rear pipes to correct angle & length to mate w/ mufflers.

Welded all cuts and slipfits except the one at the transmission x-member.

Be prepared that a perfect fit of the SCC12 requires multiple cuts and welds and you won't be disappointed. Even with the short comings it's a great value.

 

Thanks zwede- I saw you in one of the prior threads and was hoping you'd see this thread. I already planned to use their collector reducers, and the guy who I talked to at Pypes today said with my Hedman headers I'd need a 30 or 60 degree bend to connect to the X section.

So, I have two big questions for you-
Did you notice any difference in performance?
Did that X-pipe change the sound and, if so, how? Yea, that's a 2 parter
Thanks.

 

My butt-dyno isn't calibrated well enough to notice a diff compared to what I had before! But I wouldn't be surprised if it picked up 20hp or so. I had a 2.5" system with X-pipe but it was crush bent and some of the bends were very crushed. Since a 2.5" system is already marginal for a 454, I'm thinking the crush bends were hurting me quite a bit.

No real difference in sound since I already had an X-pipe.

 

Good info, thanks. You may be at a power level where it takes a good bit to feel a difference. What kind of mufflers do you have?

 

Borla stainless, pretty large body (19" long) so it takes some finessing to make them fit.

 

That's the same overall length as my Ultraflos. It may take some work but at least I know it can be done.