Now it was time for the exhaust upgrading. Having purchased the "Type-B" ECU mod from RE-Amemiya, it was unable to unleash its full potential through the previous (el-cheapo) CAT-back sports system. Whilst the CAT-back system enhanced the engines ability, it was a compromise & for that fact, destined for some one elses Cosmo. Hint = JCESE-100330

There are plenty of performance exhaust places that can cater for a system of my requirements but they all have one thing in common. In & out "ASAP". Whilst that may be a good thing for some. It wasn't for me. My preference is for the shop to take their time & ensure the best possible quality. Charlestone exhaust have been doing custom sports systems for over 15 years & the propietor (Bruce) knows his business. Importantly, he was prepared to take his time & after 2-weeks on-site, the Cosmo was almost ready to return home.

Charlestone exhaust manufactured a full mandrel bent stainless steel system as per my requirements. The key to rotary performance is un-interupted flow & no sudden bends. Larger pipe diameters are also required compared to normal thanks to the 3rd rotor. The front part is Ceramic coated for heat retention & 3.5" diameter. The CAT is a a high flow CATCO unit from the USA made for 6-Lt V8's.

As seen in these first pics, the system was still incomplete when I took them. The Cosmo had been there a week & he was still a day or two away from completion. (quicker jobs come & go between work on mine) From it looks like so far, the job is coming along well. I am looking forward to listening to the sound level. The requirement was to be quiet during cruise but decent sound levels when the pedal is mashed.

The 20B version exhaust has a pre-cat fitted like the series-6 RX-7 of 92-95. (S7+S8 = no pre-CAT) Installed into the pre-cat is the exhaust overheat sensor that sends a digital signal to the ECU via a A-to-D convertor. At a pre-determined level the ECU will go into "Rich mode" to cool the exhaust back down. Unplugging this sensor trips the "rich mode". Shorting the sensor wires leans out the entire fuel map by a few points. The way to ensure reliability is with a 50 Ohm resistor simulating normal operating conditions.

Soldered into place, the resistor mounts to the original plug the sensor was attached to. Now into place, it will not change the coarse setting of the fuel map as if it where simply cut open or shorted.

As with all custom jobs, you work slowly & surely. Custom made rear mufflers have been done & are getting fitted in this shot. They are made with rotary engine heat in mind to prevent premature failure. Chrome exhaust tips are yet to be fitted & the finished result should prove quiet shiny for admirerers of the rear end. The twin pipe section is 2.5" each side & will dump via quad 3" tips from the rear mufflers.

Despite the cost expected to be well over AUS$1500 for the completed job, its the value-for-money aspect that is more important here. Another important point, the system can't resonate, crackle or pop like some systems do. If it does the car goes straight back in for rectification.

In this shot, the exhaust was now finished & the sound was simply awesome. Not too loud, but did it flow or what... On the road was the real test & after departing with just over $2000 of hard earned cash I was out to test its abilities. Firstly, the response from the engine had picked up considerably. The boost came on quicker & the exhaust was now flowing properly as the engine was strong right through to red line. The car felt entirely different & the constant smile on my face said that this was money well spent.

The twin 3" outlet tips for each muffler was to follow the original design & are a little more classy in my opinion. I liked the European luxury tourer theme & this is the way the Marque manufacturers do there systems. The look still disguises the true potential of what lurks within, maintaining the "Sleeping assasin" styling.... Just how I like it !!