Exhaust and Intake Modification

By Blair Burn

Prior to making the modifications to the MR2 I consulted a great many performance specialists in Canberra, including Neil and Rick Bates, concerning performance mods. I was under the impression that a new chip would be the go but the following summary of comments changed that:

Based on this info it was hard for me to justify putting in a new chip. Besides that, if you do your warranty becomes VOID immediately. If you have any further info on chip upgrades please let me know. Half the trouble is some businesses are keen to sell and install one but they won't EVER commit to obtaining significant power increases.

It was recommended that I start by first freeing up the intake and exhaust, so I did. The standard air filter was replace with a K&N filter. There was no need to extend the intake snorkel to an area with increased air flow because it is already in an ideal position. It sits just above the left air scoops in the rear panel. The difference was immediately noticed when I started the car and heard a huge air intake whine from the scoop. On the road it was a little hard to tell but some rough times from 4000 rpm to redline showed a decrease of about 0.7 seconds.

The exhaust system was a real journey. The guys at Roadway Exhaust Centre here in Canberra fitted several different systems to obtain the best performance and sound. The first few systems certainly freed it up but the Mister sounded worse than Mick Doohan's GP bike. The guys made a comment that a sports exhaust is 60% performance and 40% note; I agree. The final system the guys came up with really works and it sounds great. You will be shocked when you see what it comprises:

The HSV muffler allows a huge increase in flow from the 2 litre and a nice sporty note is achieved. I put the car on a dyno for before and after power readings. The 'before' test was done prior to the air filter and exhaust being fitted.

The results follow:

A power increase of 3 kW was achieved @ 2000, 3000, 4000, 5000, 6000 rpm. The guys at dynotune claimed that an increase of 5 kW @ 7000 was on the cards.

RPM Before (Nm) After (Nm)
2000 260 290
3000 260 300
4000 340 350
5000 360 390
6000 500 505

From the results you can see that a reasonable power increase was achieved but the torque increase was beyond expectations. The result on the road was instantly noticeable with the revs climbing to redline far more quickly and smoothly.

The first run found me hitting redline before I was ready to change gears. These figures should probably be increased due to the fact that the car was dynoed with no air flow to the snorkel and the 'after' test was done on a warmer day.