Cool. I've got a '91 325i Wazavertible (Hard Top replacing floptop, forever) with not much done except a joke of a air filter replacement (K&N stock replacement) and fully open exhaust, manifolds to 4" pipe to a "why bother" muffler. Paint is coming, Wheels are coming, Interior is......maybe. Also new to the club, Thanks to the guys at River City club and their Dyno Day....tons of fun. Wife had a blast too, which makes everything that much better. So.....now what?
hi Odk, i'm inter'sted in your exhaust mods - did you remove your catalytic thing? my '85 e3 has a custom Stahl header (1-1/4" primaries) running thru the stock cat-converter to a Supertrapp muffler. I've just changed from a 3" trapp (no baffles) to a smaller 2-1/4" size w/ 18 baffles, that i'm looking to find a back-pressure setup that won't wake my neighbors while still letting me rev up freely into a down-shift. Dan the mechanic guy sez I can legally delete the cat-converter, 'cos my annual mileage is low & my car is emissions-exempt, but I wanted to ask you if you'd got a decent power-increase from removing your cat. And, isn't there a sensor-wire from the cat to the fuel-injection brain? What was your solution to that?
Exhaust. Well, Mine was done when I got the car. I bought it from my brother, and he did the work (we don't live very close so I wasn't involved) The stock downpipes, where the front and rear manifolds would join, have been directed into a single 3.5 or 4.0 inch pipe, no cats, and if there was an O2 sensor there, i haven't a clue where it went. There is one further upstream, although i can't rightly remember if it's in a crossover pipe or just one of the downpipes. That large pipe runs the stock route back to a Flowmaster (super 44 i think). They cut and TIG'd on a larger inlet pipe to fit the larger diameter. From there, out to a smaller (2.5?) pipe, angled awkwardly out towards the corner of the car, upturned at a goofy angle, and capped off by a chromed dual tip. The sound is odd. Throaty when doing a roll on "downshift and hammer", a little high on take off, beautiful IMHO at idle, and a "valve slap" downshift that is a little harsh but kinda grows on ya. It's not at all "coffee can ricer" sounding, which I worried about till I finally had another CCA member drive my car while I listened. It was the first time anyone else has driven my car in the 5 years i've had it. I'm considering changing for a single chamber turbo upstream and then having an Orange Peel type resonater downstream, just to bring a lower note. Wish I could do a true duel, as I've loved the sounds from the old I-6's that used to be in lots of trucks and cars, but afraid the quick rev and short stroke of ours will sound dumb. ok, enough yapping from me.
k, i've got my car back w/ a replacement Supertrapp - it's 2-1/4" w/ 18 baffles + cover, vice the old 3" trapp w/ nothin'. I'm getting lots more back-pressure for 'compression-braking' now, instead of virtually none w/ the old muff. Fortunately, though, I can also get a decent up-rev 'throttlle-blip' into a down-shift that accords perfectly well w/ my driving style, w/o having to play w/ the # of baffles. It's certainly quieter than it used to be, too!
