A big MAC to go...and hold the noise

[Cdnlouie]

In case anyone is making an exhaust decision soon you might want to consider this option.

As a followup to "Got a light for a MAC pipe" I finished my experimental baffle modification this week. ?Lucky sent me some great food for thought and information that influenced my direction.

I liked the resonance chamber Lucky is building into his design but felt the space inside the MAC is limited so I extended the MAC by 3.75 inches and added a resonance/silencer chamber (it does not look out of place at all). ?The idea is to preserve the deep thump as much as possible but kill the noise (especially on the highway).

I have pics of everything but need to build my website and get it linked.

It cut the sound of the MAC by 50% and as far as I am concerned no appreciable decrease in performance. ?Actually I felt more like pushing it now since it doesn't sound like it is going to fly apart.

I would like to hear a stock pipe, but I feel that this one definitely has a louder and deeper header sound. ?I cut off the inner support ring (and left it off) and added four stainless steel scrubbers (no stainless wool at the moment) for noise reduction and support of the baffle. ?The resonance chamber is an auto parts exhaust reducer 2.5inches down to 2 inches (3.75 inches long) with a 3/4 inch pipe (inside diameter) about 2 inches long (solid) welded to the end washer (at the end of the pipe) and welded to the inside of the exhaust reducer.

The final installation was a tack weld to the edge of the end baffle plate. ?I need to weld it continuously around there after I am certain that this is a keeper to eliminate minor leak and pfff sound.

I am quite certain that the increase in back pressure is not a bad thing. ?It seems to improve the carburetion response. ?It may well be fallacious to think that less is always better for the Vision. ?I really love the awesome carb throat sound, never heard that before (kind of like an old four barrel carb kicking in).

This involved about $10 in parts, mostly labour in welding and finding the right size parts to build it. ?I would like to try about a 7/8 inch end washer and pipe sometime, but I am so happy with this current version that I probably will not bother. ?It would give you a louder variation that's all.

My wife loves it and that makes it particularly valuable to me.

Louie ? :D

[Rick G]

HI Louie, A stock Vision exhaust, sounds  like a Hover with a head cold . It reminds me of a CB77, only quieter.  When I added the MAC to mine, I felt it was really no faster , but , because I could hear each exhaust pulse, it sounded like the engine was turning slower, at the time I noticed it seemed to vibrate more, possably due to the differant mounts. After 12000 miles with it, I think that the mid range is better , but top end no better.

[Cdnlouie]

I am finding with the baffle modification to the MAC I have better cold running.  The improvements continue to impress me from every angle.  It pulls stronger on initial warm up.  I am really pleased with the results.

I received a sample of stainless steel wool today from Bulldog Canada the only manufacturer here.  I think they gave me enough to wrap my baffle, but the 4 stainless scrubbers per baffle have given me all the noise dampening I need and they will last a long time without needing to be changed from soot accumulation (due to greater porosity).  I would have to buy a 5lb roll for about $75 which seems to be about the same for Lucky's site.  I have not yet found a supplier that sells it in smaller quantities.

I would like to contact MAC which is here in Canada and see if I could get baffle replacements for a reasonable price.  I would like to do another modification just for interest sake.  They must use them in other exhaust systems as well and might have them on hand.  If I could find the end plate that is all I would really need, as a 1 inch and 1/4 pipe is easily found.

Louie  8)

[Rick G]

MAC provides (provided /)  a defuser type baffle (as opposed to the absorber type)  as an option. Try a email to them and let us know.