EXHAUST

Part 1

A shop called Hangar-1 in Mexico City did most of the initial exhaust work. I researched a lot of different designs to get the right sound, style and weight. Although some work was done by my Uncle Antonio in terms of maintenance and some exhaust tips and Mofles Cuajimalpa did most of the later exhaust work. In the U.S., I also used Car's Muffler Centerlocated in Sarasota, Florida.

All piping is steel.

Originally, we went through several variations over the years until we arrived at the current design you see. We actually started off with exhaust tips (that do practically nothing for performance) that both Hangar-1 and my uncle welded on to the stock muffler. Then we moved on to an oval APC Intimidator 1021 model. After that, we removed the stock resonator and replaced it with that very same APC muffler and we had nothing but a dual tip on the end until we arrived at the design concepts shown below.

The initial design shown includes an Arvin Muffler ($30) (similar to ones on VW Jettas and some Nissans) with two entrances, two 2.25 inch pipes (I believe this was 2 inch stock at this part) with a Y-Pipe going back from a Sankei Resonator ($30) (from a Honda Accord V6) and a Magnaflow High Flow Catalytic Converter ($220) (a replacement for the original cat that was damaged on the road).

Although U.S. plated vehicles are not required to have an emissions test in the Mexico City area, you must if you want to avoid the very restrictive Hoy No Circula (Today you do not drive) program that limits even foreign-plated vehicles based on the last digit of their license plate to not driving one day out of the week at the time that I lived there, though the driving restrictions are now much more stringent. My RX300 passed this test with a cero sticker (can drive all hours and days), as stringent as California in its levels, since they first started allowing foreign vehicles to test! Many thanks to Hangar-1 . Keep in mind that during the time I was there, the gas was high in sulfur compared to U.S. gas and with less oxygen in the air given the high altitude not to mention smog and add to that the 20 million plus people living and breathing in the metropolitan area.

This RX's nickname comes from my track friends due to its paint and also due to the sound it makes like a charging bull on its 1/4 mile runs. Toro Negro is Black Bull in English, though I do refer to my RX as a she.

 

Post-Resonator view

 

 

Arvin Muffler, each tip has a 2 inch diameter.

 

 

Side view of the Arvin Muffler

 

 

Back of the Arvin Muffler (2 inch diameter on each exit there)

 

 

Continuance of piping behind the Arvin Muffler

 

 

Piping down below the RX

 

 

 

 

 

 

 

 

 

Joint from the back of the Sankei Resonator

 

That joint has a 2.5 inch diameter that opens up to the 2.25 inch twin pipes

 

 

Sankei Resonator (much lighter than that fat tub OEM resonator)

 

 

The Sankei is a 4092 model. Note the Honda marking (I am such a traitor:)

 

 

Interior view of the resonator (this resonator was later scrapped in part 3).

 

 

Magnaflow High Flow Cat (model number 94005, a 3-way with a 2.25 inch entry and exit)

 

 

 

Perspective of Magnaflow High Flow Cat and Sankei Resonator

 

 

Joint before Magnaflow High Flow Cat

 

 

 

 

 

A few of the Magnaflow cat and Sankei Resonator from the front of the vehicle.

 

 

 

My uncle had to weld this pipe shut twice in the span of four years.

 

Part 2

An improvement on the exhaust manifolds closer to engine and again handled by Hangar-1 . Total cost was close to $170 USD (a bargain). Basically, we expanded the piping from 1.75 on the front manifold and 2 to 2.25 inches on the rear manifold (it is hard to tell from the old piece) to 2.5 inches on all.

 

 

A comparison below of the old and new pipes from the front and under the engine block.

 

 

Comparison of the diameters of the old and new tubing.

 

 

A look from the rear manifold. Hangar-1 was able to use part of the original OEM piping (joint with bolts) on to the new piece.

 

 

Another look at the same area

 

 

A side view (pre-installation).

 

 

A long view (pre-installation)

 

 

A look up at the front manifold area.

 

 

A few of the front lower curve.

 

 

A view from the front of the RX.

 

 

A weld off near the front differential (drain plug on right) and immediately below the engine block and transfer case (on left)

 

 

Over the hump

 

 

Pre-merged pipes

 

 

The weld of the two joined pipes.

 

 

A view a little further back

 

 

Part 3

Hangar-1 handled this again about a week after part 2. This involved the enlargement of pipe between the Magnaflow cat and the resonator (an excellent suggestion again from TunedRX300), along with replacement of the Sankei resonator itself to a custom Hangar-1 design. It was on the same day after this modification that I broke my 123.69 km/h speed record with one of 124.92 km/h (now surpassed, too). This cost a little less than $114 USD.

 

 

With the piping between the cat and resonator, we moved from a 1.75 inch stock diameter to one of 2.5 inch. We cut the old bung from the OEM piping and welded it on to the new piping.

 

 

A view taken from a little bit further out.

 

 

A view of the Hangar-1 Resonator. The previous Sankei Resonator suffered a blow with a lot of rattling of some material that we could never fully expunge. So this sounded the best of the finalists. Much quieter and not as loud on the high frequency notes.

 

 

An interior view of that resonator.

 

 

A long view

 

 

As I mentioned it is much quieter. The acceleration is also a smoother except for a minor hesitation in the mid-to-high range rpms for the moment, but this may go away with time as the ECM adapts to it.

 

 

One final view through past the O2 sensor, through the resonator and a view of the y-pipe.

Part 4

As I mentioned I had some minor hesitation in the mid-to-high range. I had a suspect in the catalytic converter being faulty and a gas analysis test proved it out. So we replaced the Magnaflow 94005 with a 93506. This new converter is .5 inches wider with its mouth being an additional .25 inches wider. Hangar-1 again did the wonderful work on this with perfect welding. $92 USD for this converter.

Just before final welding

 

After final welding

 

Two days later (note change in color)

 

A little more torque with this converter, but just barely noticeable.

Part 5

 

 

 

 

 

 

If you notice in earlier photos there is a joint just in front of the catalytic converter. For about 8 months before the upcoming modification, I had a nasty popping noise upon acceleration from a dead stop and sometimes when coming to a stop. Turns out the joint was not fully secure, despite having its gasket and everything otherwise okay.

What was done here was to chop off the joint and replaced it with about a foot long (eventually a piece whittled down to 8 inches) of a flexible coupler. We also had to chop off some of the ends of the tubing on the catalytic converter and the front of the resonator. Thus, the 2.5 diameter width section of pipe holding the O2 sensor was pushed backward as was the catalytic converter. A new hook/hanger was also attached to the catalytic converter. All of this cost about $180 USD.

Part 6

 

 

 

 

 

 

This work was done at Mofles Cuajimalpa.

Here we replaced the earlier resonator with a Vortex muffler made by Supreme Performance model number 88106. Though it is claimed it is a 2.25 inch opening and twin 2.25 inch entries, we measured them out to about 2.5 inches. It is about 17 inches in length, about 10 inches in width and a little over 4 inches in height. Weight is about 17 pounds. All work done cost about $160 USD.

The objective here was to remove the restriction caused by the single tube resonator (that had a 3 inch opening and exit) and instead start the split in flow immediately after entering the new muffler. This muffler does exactly that instead of entering in a single pipe through much of the muffler and then splitting. Thus the y-pipe starts inside the muffler not afterwards as was before. We also put the O2 sensor into a new bung. Impressions are more of a growl than before and better low-end torque. However, later testing revealed that the gains at low end were minimal and actually high end gains were had. A km/h (mph) record was set with this setup.

The one other thing is that it is intentionally tilted downward toward the rear for aerodynamic reasons to provide an angle, instead of a flat face, for the airflow.

Part 7

 

 

 

 

 

This was a replacement piping for the earlier flex pipe shown earlier. I found the flex pipe to be extremely restrictive in terms of power, so I went to Mofles Cuajimalpa and had them make replacement piping and used part of the y-pipe in front of the flex pipe to make the y-pipe in front of the cat. Less hesitation when hitting the throttle. Length of replacement piping is a bit over 9 inches. This cost just under $40 USD to do.

Part 8

 

 

 

 

 

 

 

This particular muffler was installed as a resonator. It is made by Kire, a company here in Mexico, and was custom made for my RX300. It consists of twin 2 inch pipes, along with one 2.5 inch pipe, with the 2 inch pipes arranged to the middle and side and one 2.5 inch pipe on the opposite side. This allows the sound waves to be able to cross the entire length of the muffler instead of just halfway with a traditional 2 in and 1 out muffler. Power is felt when accelerator is half to full and the vehicle is significantly quieter with no drone present in idle or under 40 mph, where drone would normally be heard. Kire is well-known in Mexico and is used by my friends at Grillos Racing Total cost for tubing and muffler installation were just under $180 USD.

Part 9

 

 

 

 

 

 

This stock-looking muffler is actually from a BMW. It has a twin 2 inch entry/exit and has a very nice flow. The reason for this muffler was because my uncle Antonio and another uncle noticed that the current system might be too loud for sea level. Actually this muffler is quite loud at WOT, especially in heat, but is not too loud to set off every car alarm within one light year:)

Part 10

 

 

 

 

 

 

This modification was based on an APC 156013 muffler whose tips were cut off at the back (dual 2.25 inch diameter exits). Although it is 1 in 2 out, the 2 out occurs closer to the rear of the muffler. I largely got this muffler (to serve as a resonator) for reasons of sound, but also to improve lower end torque, which was lacking with the Kire and Vortex mufflers before it, that allowed better km/h (or mph) at the high end, but not as great performance on the low end. I later painted it black for aesthetic reasons to match the rest of the exhaust piping and muffler. This work was done at Carl's Muffler Center in Sarasota, Florida for $75 USD. The muffler cost $89 USD at Pep Boys.

Later on this site, I have a link to some videos (with sound) to hear this wonderful exhaust system in action.