Another Allison's Exhaust

geekdaddy

geekdaddy

X1/9 Learner's Permit...
When I started fixing-up the X I purchased a few years ago, I tried re-using the IAP header by sandblasting it real good and ceramic coating it. I knew it was a 50/50 proposition but was easier and A LOT less costly than replacing it. Unfortunately, it was far too gone and has been rusting from the inside-out. Time for a new exhaust.

After receiving lots of mixed feedback on Mark Allison's header, I decided to take a chance on it. I didn't like the look of a large muffler hanging down so low, so I opted for a CAT + smaller chambered muffler. Mark suggested it had a good rumble but was not very loud. Good thing I got the CAT -- the guy who performed my annual inspection said all 75+ vehicles in NH are required to have one. I didn't realize that -- the previous inspector didn't notice my former non-CAT exhaust. Overall, I am very satisfied and the experience has been good, but not without some small challenges/issues. Would I do it again vs a local shop? I think so. Details below along with some photos...

The good:
- It's beautiful. Looks like a work of art.
- Workmanship is seems overall very good. Time will tell.
- Bolted to the head without incident.
- Came with very good quality mounting HW, gaskets, etc.
- Exhaust note sounds great.
- I THINK it feels a little faster in the mid/upper RPM range.
- Mark has tweaked the design to accommodate the injector cooling shroud and give better access to some of the mounting locations.

The bad:
- Had a few hiccups with delivery.
- Muffler had a void in the muffler weld. Mark repaired it.
- Header was shipped without O2 bung. Mark replaced it.
- Ended up losing a few weeks to my Spring start due to ship back-n-forth. But Mark covered all the shipping costs.
- Mounting points in the heat-shield area did not line-up well.
- Mark suggested bending them (which I did reluctantly).
- I also sourced different length mounting springs to get the proper tension and alignment.
- Tailpipe exit out the passenger rear was close, but I had to bend it down and out a bit to get perfect alignment.

Not sure:
- Even with the Cat + Chambered muffler, this is louder than I expected.
- However, the sound/loudness is really beginning to grow on me.
- Sounds like a very large cat purring/growling. It's kinda cool :)
- May be uncomfortable on the highway with roof installed. We'll see.
- The injector cooling shroud now fits, but nearly touches the manifold.
- My high-temp silicon 3rd party shroud was beginning to melt/smell.
- I have an idea for using an aluminum extension near the header that may work better.







 
I can imagine it's louder...

I can imagine it's louder... there isn't any muffler there, just a couple of small resonators. I'm sure it has more power, but I personally couldn't live with the noise I assume it makes. Glad the fit and appearance make up for the lack of noise attenuation.
 
Hmmmmm... I too think it looks great and...

much of the massaging it needed would be something I would expect for any "normal" aftermarket installation. Especially when it comes to headers and exhaust systems. But...

I expect better here for the following reasons:

1. Except for the muffler change, all systems should be identical and fit and finish should be PERFECT. I don't see where any variations would come in on Mark's part... except the possibly the customer has some poor engine mounts that cause the system to be tilted or tweaked.

2. There is no excuse for the poor weld or any other quality issues as these should be thoroughly inspected before shipment. I don't think he's shipping hundreds of these a day...

3. The cost. I'm not saying they ain't worth it... just saying there is a bit o' money exchanging hands here.

I'm glad Mark made GOOD on all of this though, shipping included... as that is what a good business man would do. It would behoove Mark to ensure these parts are inspected, maybe even trial fitted on a jig... so that dollars aren't lost on shipping and the customer doesn't get frustrated with the installation and the time it takes to correct discrepancies. A win-win for all.
 
Tolerances

Hi Tony,

I agree that a high bill warrants high expectations, but I would like to caution against attributing all tolerances and variations to the aftermarket part.
Especially on an issue such as tailpipe to cutout fit, there is a long lever arm involved that magnifies variations.
If the engine sits just a small bit differently between two cars, the difference at the tail pipe may be large.
With a small stock tailpipe, there is more room for variations too. :)
 
- the guy who performed my annual inspection said all 75+ vehicles in NH are required to have one. I didn't realize that
Click to expand...

Actually not true, NH law states all NON ODBII cars are exempt and do not require catalytic converters. So basically, any car prior to 1996 are not required to have a cat.

Kinda moot point at this juncture, and that exhaust looks awesome!
 
After installing the Allison header I had to modify the metal tube located on the rear inspection panel to allow the flexible injector cooling tube to clear the header. I had a little trouble with the springs coming off of the mounting places, but eventually got them secured. I bought Mark's quietist muffler and it's still pretty loud when going through the gears. In town, I'm careful to keep the R's low so as to not draw the attention of the police. Makes me feel like a teen.:whistle: I do like the sound when going through the gears or down shifting with my foot to the floor when passing on the highway. On the open road the exhaust noise is minimal, but noticeable when passing another car.:wink2:
 
Very Nice

You've wet my appetite. As soon as I finish re-assembling my motor, and it runs....I will turn my attention to a new muffler/header system. Allison is on my short list.

Did you price out a custom job from a muffler shop?
 
I didn't price-out a system from a local shop. I'm guessing you MIGHT be able to get a stainless or ceramic-coated system for a similar price point. But there's a lot of creative work in the header. The exhaust portion seems more straightforward...

Joe F said:
You've wet my appetite. As soon as I finish re-assembling my motor, and it runs....I will turn my attention to a new muffler/header system. Allison is on my short list.

Did you price out a custom job from a muffler shop?
Click to expand...
 
Kevin -- my alternate source was generally eBay and a few online ATV custom shops. It seems our X's are fairly unique with respect to hanging exhaust components with metal springs. Most shops are more familiar with rubber-hangers.

The one's provided by Mark are (I think) stainless and approximately 70mm end-to-end. I found these springs are used by the ATV/go-kart guys and they also make them available from 45mm up to 100mm. If you search for "57mm exhaust spring" or something like that, you will find several. Common lengths seem to be 53mm, 57mm, 67mm, 70mm, 83mm, and 100mm.

I "hung" the exhaust using the included springs and found the exhaust flange was ~1 inch too far away and approximately 3/4" too low and 3/4" to the right. I could pull it into position and bolt-up the flanges but this would place a constant force on the header which I didn't like. It also caused some springs to stretch A LOT (over-stretch?) and some springs were hanging so loose they would easily fall off.

So I bolted up the header and exhaust and then measured the distance between the mounting points and my hangers. I sized the springs slightly smaller (10-15%) and purchased them. When I re-hung the header with the new springs, the flanges lined up almost perfectly in the up/down and left/right dimensions -- I bent the mounting point downward a bit to improve alignment. After that, the flanges were ~1/8" apart and required almost negligible force to bolt them up so I was satisfied.

Kevin B (Asheville said:
please share the source for the alternate springs.
Click to expand...
 
I think we basically agree Ulix...

I said initially that these kinds installation issues were pretty normal... as well as the tailpipe fitment probably needing adjustment is most cases for the same reasons you noted.
 
Mark's system is also tested and proven...

to be quite effective. Lots of time and thought went into these... despite some little problems.
 
After ~125 miles of use...

I really like the exhaust note of this system. However, I'd like to cut-down on the drone a bit. Other purchasers of this header & exhaust warned me about drone and it's not awful but a little more than I'd prefer. Was doing some internet searches and found that several folks have used inserts after the collector which apparently reduce drone considerably, noise a little bit, and don't sacrifice power. In fact the manufacturer has dyno results which show low and high-end power is nearly the same.

These devices have to be secured inside the pipe which means welding or riveting which I'm not too crazy about. However, I may consider purchasing the short version and welding it into a flange which can be inserted between the header and the exhaust pipe. For $50 might be worth trying...

http://www.carchemistry.com/2-disk-insert-2-1-2-diameter/
 
Whoops -- never mind. I have a CAT and just noticed this device must be installed downstream from it. For me, this involves more work and cutting/welding of the existing setup :(
 
Regarding Sound

I spoke to Mark a while back about this set-up and he said they had a variety of muffler options ranging from soft to medium to loud. Can you tell me which muffler you have.

As far as sound is concerned, my only reference is an ANSA quad (twin duals) muffler I installed on my 78 X. I loved the sound.

BTW, did you make new hangers?
 
Joe -- I asked Mark for the quietest small-ish muffler he could use. The larger one he had recently offered others hung rather low below the valence. Mark suggested the "turbo-tube" configuration that I have and said he didn't feel it was very loud -- especially with a CAT installed. It's not loud like a Harley but it's substantially louder than stock IMO and has some drone at road speed.

At one point he offered a muffler larger than the turbo-tube but smaller than the one he uses now. It's the one shown on his website. He said the cost on that one (flowmaster???) had increased in cost and was now less desireable.

I didn't make my own hangers -- just painted the OEM ones I had black. Was hoping to score some stainless hangers that were made available a few years ago but none were available.
 
car chemistry

I was just reading their web site and it says the insert can be placed in the tailpipe to act as a second muffler. If you want the full effect of the insert, then they need to be placed closer to the engine. I might get one and put it in the tailpipe to cut down on the drone.
 
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