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Exhaust System Upgrades
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Pelican Technical Article:

Exhaust System Upgrades

Bob Tindel

Applicable Models:

Porsche 911 (1965-89)
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     In our continuing effort to provide the very best selection of OEM and aftermarket parts for your Porsche, Pelican Parts staff recently met with the manufacturers of GHL exhaust systems.  GHL makes mufflers and headers for 1978 and later 911s through 996, Turbos and Boxsters, as well as 944, in various configurations of inlets and outlets.  They are currently developing headers and muffler for the 914-6.  All of their pieces are made from top-quality 304 stainless steel, beautifully TIG-welded, and highly polished.  (Figure 1)  Their products are shipped with the necessary clamps, bands, and gaskets to complete the installation.  (Figure 2)  GHL proudly backs all of their products with a lifetime warranty.

     I have tried several exhaust systems on my Porsches over the past 30 years, and always wound up taking them off and putting the stock system back on for one reason or another.  Usually it was because they sounded buzzy or raspy, or were just too loud.  This is the first system that I would rate as outstanding in every respect.  The welding is so delicate it must have been done by very talented mice.  (Figure 3)  The flanges are at least as thick as stock.  This prevents the flange from warping and leaking, as some other aftermarket products with thin flanges are prone to do.  The muffler was an exact fit on my 911SC, with no need to bend or grind anything, or enlarge any holes.

     GHL mufflers are designed with a separate tailpipe.  This allows rotation and positioning of the tailpipe to get the outlet exactly where you want it.  Additionally, GHL makes both three- and four-inch tips, so you can choose what you want, or change it later if you change your mind.  The tailpipe slips snugly onto the muffler outlet, and is held in place by a heavy stainless steel clamp.  (Figure 4)

     This article describes the installation of the GHL muffler on Bob Tindel's 1983 911SC.  Your car may differ slightly.

     A day or so before you start this project, I recommend spraying all of the fasteners, including the ones that hold the front of the catalytic converter to the heat exchangers, with penetrating oil.  I have had excellent results with Wurth Rost-Off, and I have heard that PB Blaster is good, also.

1.   Begin by jacking up the rear of the car, and placing it on jack stands.  I put the jack stands under the torsion bar covers.  (Figure 5)

2.   Remove the three bolts that connect the rear end of the catalytic converter to the muffler inlet.  (Figure 6)

3.   Loosen the two muffler mounting bands (8mm allen-head) to the point that they can be slid off the muffler bracket.  (Figure 7)

4.   Support the old muffler, slide the mounting bands toward the outside of the car until they clear the muffler bracket, and lower the muffler.

5.   Place the new mounting bands loosely around the new muffler, and raise it into position.  Slide the mounting bands onto the muffler-mounting bracket, and install the mounting band fasteners loosely.

6.   Connect the catalytic converter to the muffler inlet, but don't tighten the fasteners yet.

7.   Position the muffler in the desired position, ensuring it appears level under the car.  You may need to loosen the fasteners connecting the front of the catalytic converter to the heat exchanger.  A little looseness at the front of the catalytic converter will allow a lot of movement at the rear.

8.   When you are satisfied with the position of the muffler, tighten the mounting bands, and then the remaining fasteners.

9.   Rotate the tailpipe to position it as desired, and tighten the tailpipe clamp.

     To me, the sound of the GHL is its top feature.  I can best describe the sound at cruising speed as the purring of a very large cat.  It is a deep, throaty tone, immensely enjoyable, but not one that will become annoying or give you headaches on long trips.  It lets you enjoy the music of your Porsche engine, without upsetting the neighbors or attracting unwanted attention from The Man.  It sounds awesome winding through the gears.

     The motto at GHL is "We take the "Rezz" out of resonate!"  I can confirm that I didn't detect any resonance or unpleasant noise from this muffler at any speed or RPM.  As an added bonus, the freer exhaust flow provides a noticeable horsepower increase-up to 30 HP at the wheels on a Turbo, fitted with GHL headers and muffler.  The Turbo also spools up about 750 RPM sooner.  The sound of this system will put a smile on any Porsche owner's face, and it looks great on the car.  (Figure 8)

     If you need any parts, please call our Parts Department (toll-free) at 1-888-280-7799 for prices and availability.

Hope this helps,

Bob at Pelican Parts

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Comments and Suggestions:
werneru Comments: Hi,
I live in Australia.
I have a problem with my exhaust system that I’m trying to fit to my 2004 Porsche Boxster. I purchased a 2nd FVD full sound system form
someone who had it on his 2003 Boxster. Both models are S. The problem I’m having is that I bought it of a car that has the manual transmission. My car
is the auto tiptronic. The header on the right hand side hits hard up against the water cooler pipe and doesn’t seem to fit right. I had a local exhaust installer try to fit it yesterday but was unable to do so. I really need some help here. We still left the FVD muffler on for the time being and had to keep the original headers and cats on until we find a solution. A few questions need to be answered I have listed them below.

Does the automatic version of the Boxster have different headers to the manual to allow for the cooler pipe that the manuals don't appear to have?

If the headers are the same how do I re-route the water cooler pipe and not have it hard up against the extractors? There seems to be a T junction which makes it difficult to re-route near the extractors sit.

With just the FVD muffler fitted only, there is an awful drone between 2000 and 3000 rpm. Will this go away with the full system?

What do I need to do to fix all the problems above?

On the FVD web site there is nothing about ordering for a manual or auto.There are 2 photos,are they of the same system?

Is the exhaust system suitable for automatics or are automatics prone to droning due to their set up?

If any one can answer as soon as possible I would appreciate it and is there anything else I need to purchase then let me know and I will do so.
October 7, 2014
  Followup from the Pelican Staff: I am not familiar with FVD headers. I do believe the factory headers are the same between manual and autos.

These are questions are best answered by FVD.

The sound may get louder when you install the headers. - Nick at Pelican Parts
kiwi911 Comments: Hi there are these ghl mufflers available on pelican?
Thank you

Aadjan van Holst

New Zealand
October 27, 2013
  Followup from the Pelican Staff: Yes, Not sure what vehicle you have, but here are a few of them:

http://www.pelicanparts.com/cgi-bin/ksearch/PEL_search.cgi ?command=show_part_page&please_wait=N&make=POR&model=944M§ion=EXHprf&page=1&bookmark=0&part_number=PEL-944THK

http://www.pelicanparts.com/cgi-bin/ksearch/PEL_search.cgi ?command=show_part_page&please_wait=N&make=POR&model=944M§ion=EXHmuf&page=1&bookmark=3&part_number=PEL-944TM4 - Nick at Pelican Parts
Charlie Comments: My 88 Manual Base 944 has reach an age where the state no longer requires a catalytic converter or emissions test. What should I know or keep in mind when replacing the cat with a straight pipe or if I hollow out the cat effectively creating a straight pipe.
June 25, 2013
  Followup from the Pelican Staff: My only suggestion is to put a resonator in place of the cat. Otherwise it may become too loud for your liking.

Hollowing it out will give you a straight pipe, more or less. - Nick at Pelican Parts
Truckman Comments: As Buckski says, GHL no longer provide a muffler for Porsche. However, I manage to get one and install it on my car. Great muffler, easily installed and sounds great. Too bad that they no longer manufacture it for a Porsche.
November 24, 2012
  Followup from the Pelican Staff: Thanks for the additional Info. We appreciate it.
- Nick at Pelican Parts
buckski Comments: No Longer Available. - Its a shame but GHL http://www.ghlexhaust.com doesn't make any Porsche Exhausts any more as it seems. Only Chevrolet, Mazda & VW. Looks good and sounds good from what I see on Youtub.e
August 21, 2012
  Followup from the Pelican Staff: Thanks for the additional Info. We appreciate it.
- Nick at Pelican Parts
Domd Comments: not sure this is the correct place to post, is it possible/recommended to turbocharge a naturally aspirated 944? if yes are there any applications currenly available on the market that contain all the hardware necessary to make the change?
October 13, 2011
  Followup from the Pelican Staff: I would say it is possible. As long as you keep the boost low.

I opened a post in our forums. A Pelican community member may be able to answer your question.
- Nick at Pelican Parts
LarryHughes Comments: Your 944 likely has the exhaust heat shield loose. Get under the car - either put it up on stands or lose some weight - and trace the exhaust from front to rear. Near the catalytic, you'll discover a shield that is effectively an outer tin surround. It rusts at the weld on both ends and then rattles. There are probably some really elegant ways to fix this. I'm inelegant - I too tin ships and cut the damn thing off. Which is probably one of the first steps in fixing it anyway. No detrimental effects I could see and the rattle is gone.
February 19, 2010
  Followup from the Pelican Staff: Thanks for the input on this one. We appreciate the help.
- Nick at Pelican Parts
Fliermike Comments: Any suggestions on a buzzing vibration rear of car, possibly an exhaust heat shield. Any history of this problem?
88 944 NA
October 13, 2009
  Followup from the Pelican Staff: I hate these types of problems, you almost have to ride on the rear bumper of the car on a skateboard to hear them properly. I would check everything under the car, and if you can't stand it any more, maybe put the car on a rolling dyno to see if you can identify the noise. - Wayne at Pelican Parts  
Mike Comments: My 88 Manual 944 has a small round box on the rear muffler pipe immediately after the cat joint. In the on-line parts catalogs this extra box is not shown, what is the difference?
Thank you.
August 26, 2009
  Followup from the Pelican Staff: I'm not sure, it may be something from a European car, or maybe just a resonance box from an aftermarket muffler setup. If you can, upload a picture here. - Wayne at Pelican Parts  
Zachvh3@yahoo.com Comments: Does the exhaust manifold for the 1984 Porsche 944 NA have the same bolt pattern as the 1985/5 Turbo? For instance can I use the turbo manifold off of the newer turboed cars on my NA 944 to turbo it? Thanks!
August 9, 2009
  Followup from the Pelican Staff: That's a good question and I am not 100% sure. i think they are different.

I opened a post in our forums. A Pelican community member may be able to answer your question.
- Nick at Pelican Parts
June 25, 2009
  Followup from the Pelican Staff: That would probably be similar to just having open headers, which would be extremely loud for street use. - Wayne at Pelican Parts  

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