Hi Folks,

This is a 'progress' report on the effects of the Euro airbox and a free-flow exhaust on a 96 M3. Since the price of the SuperSprint exhaust has reached $800, bringing one's M3 to Dinan for exhaust modification ($644 installed) is now a cost-effective alternative. This quoted price is for modification of the owner's exhaust having less than 5-8k miles on it (mine had 3200 miles before mod'n). I drove my car up to the Bay Area from San Diego to have the modification (coincident with a business trip and the M3 get-together last Tues- it was great to meet the faces of many people on this list)).

My 96 M3's exhaust is the first to be subjected to mod'n by Dinan and I was hoping that (i) it would be uneventful, (ii) similar to the 95 M3 exhaust modification and (iii) completed within a single working day. However, the 96 M3 exhaust turns out to be very different from the 95 M3 exhaust; the internal tubing diameter is larger and the plumbing pattern is different. Dinan did their best to improve flow and avoid excessive noise and harmonic resonance. Ideally, they would perform multiple iterations with road tests, but my car could not be left for multiple rounds of testing. Nonetheless, their first attempt has been relatively successful. FYI- the downpipe and headers of the 96 are different from the 95 too. Rather than fusing the headers and then splitting, the plumbing is kept separate.

Performance: with the Euro airbox and exhaust, the engine revs much more freely and has more power at higher RPMs (>4000). However, there may be a slight loss of low-end torque- a flash eprom upgrade from Dinan or Jim C. should remedy this? Accelerating from 70-100+ mph is definitely faster; downshifts feel more effortless.

Noise: At idle, the exhaust is barely louder than stock but deeper in tone. At high RPMs, the exhaust is louder but appealing to most who hear it (we were rev'ing engines in the parking lot of Scott's at the Bay Area M3 get-together). Compared to the stock 95 exhaust, this first iteration of the 96 modified exhaust is significantly louder- but not ear-splitting (the volume is similar to the Dinan exhaust on my E30 325i 2.8L Stroker). The 96 M3 exhaust is slightly louder than the modified 95 M3 exhausts that I heard at the M3 get-together; however, its tone was lower-pitched than the stock or modified 95 M3 exhausts.

Harmonic resonance: There is a slight resonance at 1500-2000 RPM on some road surfaces when lugging the engine in too high a gear. However, with normal acceleration from a standing start, one just zips past the resonance and all one hears is a healthy roar. Resonance can also be heard at 2800-3200 RPM when the car is driven sedately at low acceleration rates or when under load (such as lugging the engine uphill behind traffic). Opening the sunroof or windows reduces the resonance. Better yet, changing RPMs or downshifting avoids the resonance. Fortunately, as more 96 M3's undergo this modification and help R&D, mine will be upgraded at no cost.

dan

96 M3 Boston Green/Modena, Euro airbox & Dinan exhaust-- snorkel &

suspension upgrades next! http://dsrna.agi.org/bmw_96M3.html 87 E30 325i Dinan 2.8L Stroker, Dinan chip/exhaust/Stage 3 suspension, LSD,

     extrude hone intake manifold, E30 M3 alloy lower control arms w/ offset 
     bushings. 58k miles, now for sale:  http://dsrna.agi.org/dinan325i.html