hey everyone, I am thinking its time for a new exhaust system on my 72. I still have the original dual system on it with some turbo mufflers cut in. I'm not interested in Flowmaster loud, but the 455 deserves a deeper better tone than what I'm getting now.

I'm looking at a DIY system from Pypes or some other vendor vs having a shop do a custom job. Just looking for some input on what others have done and if you're happy with the results.

 

I just installed a Pypes 2-1/2" system with a pair of Dynomax Turbo mufflers on my '72 442 convertible; I put the car up on blocks so I had pretty good working space, but it still sucked working on my back. The 2-1/2" tail pipes seemed enormous compared to the factory 2" pipes and the routing is different than the factory pipes, but they still had reasonable clearance at all the critical points. The kits don't come with head pipes, but I have headers so that wasn't and issue for me. I like the sound of the Dynomax mufflers, nice mellow throaty sound without the droning at highway speeds. A couple of tips: 1. Use jack stands to help support the pieces until you start tightening, 2. Buy some band clamps, don't use the standard u-bolt clamps. The band clamps don't distort the pipes when you tighten them so it makes disassembly and reassembly much easier. 3. Assemble the system back to front, then cut down the middle pipe to length. I think I bought the kit from Summit during a Labor Day 10% off sale.

Rodney

 

Hey Rodney, thanks for the reply. Did you do an H pipe on yours? Also, did you experience any leaks by just clamping it all together with no welding?

 

At the suggestions of our forum members used Gardner's concours on a '69 442 with their louder muffler (turbo). It is truly a very nice quality system $$$$ that sounds great. I'd describe the sound as you definitely hear it, you know it's a muscle car but it is not close to being annoying.
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Sounds better than the stereo.

 

Like CDROD, I have a PYPES 2.5" system, but it is not installed yet. I've mocked it up both on the driveway and under the car. I have a number of parts yet to install under the car, this summer, and the exhaust, along with the axles, brakes, etc., etc., will all be included. I went for the X-pipe, rather than the H-pipe. Since I was in no rush, I monitored the sales for quite a few months before I picked up the set. When I pulled the trigger I got about 20% off. It was either JEGS or Summit where I got mine.

 

Jeff:
I did not install the "H" or "X" pipe which, I'm sure, made my install much easier. I installed dual cats right after the headers and wanted to be able to remove them if necessary. My car is a convertible so I didn't want a smelly "top-down" experience, I've also got a throttle-body EFI (not a carb) so i can control the AFR better than a carb making the cats more practical. No leaks that I can hear. I only used the band clamps on the collectors, cats and the muffler inlets; I used the standard U-bolts for the rear hangers as I didn't see the need for the additional expense (band clamps are $10-$15 ea. compared to a $3 U-bolt clamp). I've already had to disassemble the exhaust from the mufflers forward to drop the trans and everything came apart without too much banging and cursing! I paid $288 back in 2017 for the stainless SGA-29 kit, purchased through Jegs.com. The 2-1/2" trumpet tips from Pypes were another $75, my prices include shipping costs.
Rodney

 

One thing to consider is the duty cycle - in other words, how often will you drive the car and under what conditions? Most kits consist of mild steel (cheap and easy to bend) or aluminized steel (relatively inexpensive and easy to bend but with an aluminum based coating on the EXTERIOR for corrosion protection). If you do short driving or the car sits in a humid environment, expect corrosion. The aluminized systems might still look OK on the outside but keep in mind moisture will collect on the inside - where there's no coating.
Mandrel bent tubing is more expensive but eliminates restrictions at the bends. Note this will not look like a 'factory' system.
I installed a Flowmaster 'American Thunder' system in my '69 442. I did use the Flowmaster mufflers but you can put any brand mufflers you want on the rest on the system. It's mandrel bent and has an H-pipe (my preference over X). Two things sold me on this kit; 1) it was available in stainless steel which most others are not. It's 409 (304 is better but ridiculously expensive) and will outlive the car given the amount it's driven, and 2) was available with straight tailpipes which mounted exactly in place for the trumpet tips. All I had to do was trim the length and weld on the tips.
I went with a 2.5" 'header back' system and it came with stainless band clamps and everything was high quality and fit great. I purchased 2.5" stainless downpipes from Pypes which will mate to W/Z manifolds or Thornton's short tube headers (latest design) and these transitioned perfectly into the Flowmaster system. Pypes also offers polished stainless 2.5" trumpet tips which I used. Fit great. The only issue is "Pypes" is engraved on a visible surface. It's small but there if you look.
No welding other than the tips and everything is tight. I've been extremely happy with the system.
I've heard good things about the other systems - just trying to give you a little more information to help with your purchase. Good luck.

 

I put the Pypes 2.5” stainless system (street pro mufflers) with an X pipe on my 72 Supreme convertible. I used the Pypes big block down pipes. The down pipes needed to be cut to fit, I also had to “work” on the flanges to make them fit without leaking. I had to do some bending to get the tailpipes to fit through the bumper notches. Finally I welded the the system together. The pipes are mandrel bent, very high quality system. It did need a good amount of tweaking to fit up tight.

 

Jeff, do you intend to change headers too, or update the manifold/headers back?

Just to share my recent experience with exhaust...
I have a 72' 350 with a 4-speed. My previous exhaust setup (from the previous owner...ugh) was some no-name long tube headers into a mixed bag of 2.5" and 2.25" piping with two Thrush mufflers (no crossover). It sounded OK at full song, but it was sharp/cackley and simply too loud for my preference with casual "around-town" type driving. I saved up my pennies and just finished installing ARH headers into a 2.5" Magnaflow system with an X-pipe. It's like a whole new car, it's incredible. The timbre/tone is appreciably smoother and really emphasizes the bass/baritone tones. Despite the mufflers being a straight-through design, it's noticably quieter around town and cruising on the highway under light load (which I understand can happen with an x-pipe). When I stomp on it, she's still got plenty of bark. Aside from the tough pill to swallow of the cost, I'm really happy with it.

If you're in MN (just taking a wild guess ), I'd be happy to meet up sometime.

 

Dave26 - you mentioned using big block downtubes. I have a small block, and as far as I can tell nobody makes small block downtubes(?). Was the cutting modification you mentioned due to using the BB downtubes on a SB, or do you have a BB and the pipes simply didn't fit well?

Or in other words, did you just show that you can use the BB downpipes for a SB application w/ some minor tweaking?

Thanks.