In the past five installments we've witnessed cosmetic improvements to both the exterior and interior of our '97 M3 sedan. In et 5/08, we swapped the alternator for a 140 amp unit. So while the car is more pleasing to the eye, our butts were ready for more power. The last performance enhancements for our M3 came in et 12/07, when we saw a gain of more than 20whp with Eurosport's stage 2.5 M50 intake manifold kit with injectors, software, a 3.5" MAF, plus air filter. So inevitably, the next step was always going to be the exhaust ...
Corsa Performance Exhausts has utilized aeronautic soundwave cancellation technology to create its patented Reflective Sound Cancellation (RSC) technology. The result is a free-flow, straight-through design with a sporty sound, but a quieter idle and no droning.
Corsa teamed up with UUC Motorwerks for the E36 M3 to sell its exhaust systems to the BMW crowd. So we called UUC and ordered the RSC36 cat-back system, which reportedly flows 37% better than stock.
During our previous alternator installation we noticed a cracked water pump pulley - the second on four M3s we've owned! Fortunately, UUC has its 6061 aluminum pulleys, which under-drive the water and power steering pumps to liberate engine power. And we'd never have to worry about cracking the plastic pulley again! UUC doesn't really recommend changing the alternator pulley on a street car because it makes an insignificant difference but voltage-sensitive components can suffer.
Next up was a throttle body upgrade. With a 68mm (2.7") bore on both the M52 and M50 intake manifolds, the 64mm (2.5") throttle body on these engines becomes a restriction. Riot Racing offers the only 68mm throttle body we could find to match the intake manifold. Riot also uses an aluminum throttle plate that's only 1.5mm thick for improved airflow around it when the throttle's open. Through this combination, they report an 11% improvement in flow over stock.
Our last upgrade would be to the ignition system. With over 137k miles on the odometer, the stock ignition and Denso Iridium plugs had performed flawlessly but we decided to create a stronger spark with Bavarian Autosport's ignition coils, which are direct replacement parts
After speaking to Bav Auto, we were told to expect slightly improved fuel economy rather than a significant power increase. Yet, if cylinder pressures are higher from forced induction, or the spark is weaker through high mileage, we should see a gain over stock coils.
With all four upgrades ready for installation, the car was taken to Modified by KC, a shop that cares for a large number of modified European cars in the Kansas City area. With a service shop and Dynojet 424x dyno, MKC was willing to help us install these parts and tested them. We'll give you the install tips this month, with the dyno numbers to follow in the January '08 issue.
 Stock exhaust vs UUC/Corsa...  Stock exhaust vs UUC/Corsa RSC36. The RSC36 looks, flows and sounds better than stock. It also shaves about 20 lb |  Using 12mm and 13mm sockets...  Using 12mm and 13mm sockets or wrenches, remove the nuts that fasten the cat-back exhaust and catalytic-converter flanges. WD-40 will help loosen them |  With the exhaust out, transfer...  With the exhaust out, transfer the hangers to the new exhaust using a 13mm wrench. Notice our rubbers were cracked (common on high mileage M3s). You can order OE replacements from Bavarian Autosport, saving you money over the dealer |
 The UUC/Corsa RSC36 exhaust...  The UUC/Corsa RSC36 exhaust installed - a perfect fit |  UUC underdrive pulleys replace...  UUC underdrive pulleys replace the pulleys for the water and power steering pumps. A slightly longer belt is also included |  The larger diameter UUC pulleys...  The larger diameter UUC pulleys under-drive the accessories. They won't crack either, unlike our plastic factory water pump pulley on the left |
 The bore of the Riot Racing...  The bore of the Riot Racing OBD2 throttle body is 4mm larger than stock, matching the 68mm bore of the intake manifold. The CNC aluminum throttle plate is also thinner, allowing a reported 11% improvement in flow |  Remove the throttle position...  Remove the throttle position sensor clip: With a screwdriver, undo the traction control boot and pull it back. You can now access the 10mm bolts securing the throttle body. If your car still has the coolant lines attached to the throttle body, remove these by prying off the single-use clamps with a screwdriver. We capped the coolant lines from the motor in Part 2 to avoid increasing throttle body temps |  The throttle and cruise control...  The throttle and cruise control cables run underneath. Remove by carefully prying them from the factory ball clips. Be warned, if you break the plastic clips RR cannot accept your core (which saves you $100) |
 Removing the cables from the...  Removing the cables from the brackets is the most time-consuming part. Good luck trying to save those plastic boots - they crack upon removal. Thankfully, it didn't affect throttle body actuation |  RR can sell you a new 0-ring...  RR can sell you a new 0-ring gasket for your throttle body. We used our original, which was in good shape |  Transfer the throttle position...  Transfer the throttle position sensor to the new throttle body |
 Finish by plugging in the...  Finish by plugging in the TPS sensor |  To access the ignition coils,...  To access the ignition coils, remove the oil cap and pry off the two valve cover clips with a screwdriver. Remove the two 10mm nuts and pull off the valve cover |  Pry off the ignition coil...  Pry off the ignition coil plugs with a small screwdriver if you can't do it with your fingers |
 Each coil is held by two 10mm...  Each coil is held by two 10mm bolts. Remove them and pull the coils up by hand. If the boot gets stuck on the spark plug, pull them with pliers. Notice the ground wire on cylinder #1. Ensure it goes back the same way. The same goes for another on cylinder #6 |  The Bavarian Autosport ignition...  The Bavarian Autosport ignition coils take 30min to install at most |  Stay tuned to discover how...  Stay tuned to discover how the exhaust, pulleys, throttle body and ignition coils fare on Modified by KC's Dynojet. We'll also have tips on how to properly dyno a car like the E36 M3 |