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Qball · 06-30-2010, 03:09 PM

I need a complete exhaust from down pipes to tail pipes. I've pretty much made my mind up on a PYPES 2.5 inch system but I'm waffling with the muffler choice. I'm leaning toward the Race Pro muffler as opposed to the Street Pro but I'm concerned that it may be too free flowing for my car. It's a '67 GTO, TH400, log type manifolds, stock 335 hp cam, Edlebrock 600 CFM carb, A/C car with highway gears. The car is used on the street only. I'm leaning toward the Race Pro because it's advertised as a PYPES's quietest muffler, and I'm not looking for an obnoxiously loud car. According to PYPES, the Race Pro should not be used in lower horsepower cars as it may cause a loss of low end torque. All things being relative, is my car considered a lower horsepower car?

Is my concern valid? Should I go with the Street Pro, instead?

PMDRACER · 07-01-2010, 12:15 AM

The log type manifolds are a major restriction. You don't need to worry about loss of backpressure from the mufflers. You're choking that motor with the cast irons before the exhaust makes it out of the head.

I wouldn't go with the Race Pros if you are worried about interior noise. Stick with the Street Pros. There's no way that the Race Pro's are the quietest muffler.

david400 · 07-01-2010, 12:36 AM

Race Pros are way loud arnt they straight through muffers? Street pros should be quieter,

gtorich · 07-02-2010, 07:44 PM

I didn"t know how to put in this thread, but if you do a search on "Street Pro" mufflers i have a sound clip there , its from 10-10-2007.

Rich

tripwr1964 · 07-02-2010, 10:45 PM

here is one of mine with street pros and 2.5" x-chg and rare ho manifolds.
http://www.youtube.com/watch?v=T6Cm5aLlOAA

tripwr1964 · 07-02-2010, 10:49 PM

btw, i find mine as advertised. noticeable at idle, mellow at cruise, get some attention at wot. cruising down the road 90% of time, no problems, nice and smooth.

Qball · 07-02-2010, 11:39 PM

Quote:

Originally Posted by gtorich

I didn"t know how to put in this thread, but if you do a search on "Street Pro" mufflers i have a sound clip there , its from 10-10-2007.

Rich

I found it, Rich. It sounds pretty cool!

Quote:

Originally Posted by tripwr1964

here is one of mine with street pros and 2.5" x-chg and rare ho manifolds.
http://www.youtube.com/watch?v=T6Cm5aLlOAA

tripwr, that sounds sinister! I love it!

PMDRACER · 07-03-2010, 04:23 AM

Found the video I took of my '71 with the Pypes 3" kit and Goerlich XLerator 18" mufflers, which are built the same way as the Race Pros.

Mine is the 3rd video from the top, right column.

http://www.pypesexhaust.com/sounds-gm-abody.html

R68GTO · 07-03-2010, 09:42 AM

I installed the Pypes 2.5 system with x-pipe connected to stock logs. My engine is basically stock 400 with auto and a/c, 2.93 rear gears. I ended up with Dynomax Super Turbos 20" case and am extremely pleased with the sound. Nice rumble at idle, quiet when cruising (even with the top down) and a little more aggressive when you get on it. Pypes has a sound clip on their site (installed on a white 68 vert). They gave a little warning about low end torque loss, if there is I didn't notice it.

Qball · 07-08-2010, 12:12 AM

Thanks for all the advice. After doing some more checking, listening to audio files, etc... I did go with the Race Pro mufflers. If they're too loud, I may have a set of gently used Race Pro mufflers for sale!

I started the swap tonight. Both studs on the pass side manifold promptly snapped off

So I'll finish up tomorrow.

Here's some pics of the new and old, nasty exhaust.

Which down pipe arrangement is correct? Pic 4 or 5?

ta man · 07-08-2010, 01:02 AM

I love the old exhaust in the shop new stuff in the house!

david400 · 07-08-2010, 11:55 AM

It is nice to see that im not the only one that knows what a living room is for LOL .
I had race pros with headers and 3 inch x pipes dumped before the axle and they just screamed , i had to pull them and was able to sell them on the board here , they were to loud for me , But with manfolds and running all the way back they should be some what milder.

Qball · 07-08-2010, 01:19 PM

Quote:

Originally Posted by david400

It is nice to see that im not the only one that knows what a living room is for LOL .
I had race pros with headers and 3 inch x pipes dumped before the axle and they just screamed , i had to pull them and was able to sell them on the board here , they were to loud for me , But with manfolds and running all the way back they should be some what milder.

My wife didn't even raise and eyebrow when she saw that. I don't suppose anyone can tell me which down pipe is the left and which is the right? If you look at pics 4 and 5 it shows them in each side.

Qball · 07-13-2010, 08:44 AM

Well, I ended up with the Race Pro mufflers. I completed the install Sunday night and I must say it sounds very nice. Not nearly as loud as I anticipated. It was quieter than the rotted out pipes and mufflers I had been running. Not much drone to speak of. Installation was a bit challenging. It would have been much easier with a second set of hands and a lift. It's true that the X-pipe really changes the exhaust tempo.

I'm very happy with this exhaust.

I used the supplied clamps. Is there a product I can use to help seal the pipe joints? I've tightened the heck out of the clamps and I still seem to be getting exhaust seepage.

david400 · 07-13-2010, 08:56 AM

Glad you like them ,, And yes you can us a stainless band clap there about 4 in. long and they work nice , there not cheap , i picked some up at Oreilys Auto Parts .

grivera · 07-13-2010, 09:10 AM

Quote:

Originally Posted by Qball

Well, I ended up with the Race Pro mufflers. I completed the install Sunday night and I must say it sounds very nice. Not nearly as loud as I anticipated. It was quieter than the rotted out pipes and mufflers I had been running. Not much drone to speak of. Installation was a bit challenging. It would have been much easier with a second set of hands and a lift. It's true that the X-pipe really changes the exhaust tempo.

I'm very happy with this exhaust.

I used the supplied clamps. Is there a product I can use to help seal the pipe joints? I've tightened the heck out of the clamps and I still seem to be getting exhaust seepage.

That's a nice looking exhaust. Any pics of the final install? I just installed a RARE dual system one on my 69 bird (alone) in my driveway using Walker band clamps and will take it to a shop for final fit. The clamps came with a tar-like material which I suspect is Walker's Acousti Seal; many here suggest that you use it to seal the joints. It's my understanding that you can buy a tube of it at Napa...

PMDRACER · 07-13-2010, 11:47 AM

Instead of clamps, take it to a muffler shop and they can weld it up. No leaks, no worries, no more ugly (IMHO) clamps hanging down.

rolling money pits · 07-13-2010, 03:31 PM

WTH happened to the passenger side muffler?? looks like somebody hit it with a sledgehammer.

ditto on the walker acustiseal for the joints, that with band clamps should eliminate any leaks.

Qball · 07-13-2010, 04:04 PM

I'll try to get some pics of the final install. I think I should take it to a muffler shop to have it fitted a bit better.

Money Pits, I think that bloated muffler was due to a back fire. That's the shape it was in when I got the car.

Jim Hand · 07:48 PM

Q Ball, some friendly advice -
Do not have your complete exhaust system welded. If you do, you will never be able to remove the transmission and possibly the driveshaft, and for sure the tailpipes.

Welding is clean and positive and will look good and stop leaks. But it also makes the entire system one giant solid system that will be much more prone to resonate, vibrate, and rattle. If you do have it welded, add several disconnects using two or three bolt flange connectors so you can disassemble it for removal.. Assure that all hangers and connectors are as soft and flexible as possible.

I strongly suggest it be assembled with normal compression U clamps or the new style wrap style clamps. Use a filler material, such as Acousti-seal or even high temp RTV to seal leaks. Then tighten the clamps only tight enough to physically hold the pipe together. Do not clamp tight enough to compress a ring into the pipes - it will be about impossible to remove. In other words, don't use an impact wrench to tighten the clamps! Using a hack saw, make four evenly spaced one inch cuts from the outside pipe/muffler ends and place the clamps about at the end of the cuts. Then, a little hammer work and solvent allows removal for replacement, repair, or even exchange. See Topic "Cut muffler inlet/outlet" directly below for more detail on cutting/fitting pipes.

And most important of all is this: Start installing the tailpipes first, and work forward. That assures good clean fit of the tailpipes without any butchering. Some cutting, and even welding; may be necessary by the time you get to the front but it will be out of sight and also easier to fit because there is generally more room and flexibility in locating the components.

Again, use the best possible hangers throughout for the quietest and smoothest possible system. I speak with great authority on this subject as we have tested and installed dozens of systems and mufflers through our 50+ years of running Pontiacs, and also the extensive testing we have completed on exhaust systems.

A brief example of some of our testing is at:
http://www.pontiacstreetperformance....p/exhaust.html

You have a good system and it will work very well for you. But planning and the best possible installation will make it even better, plus allowing for later maintenance and changes.

Jim Hand

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