hey whats up fellaz, new here and new to e30's, never owned a bmw before, only rice rockets. anywayz what i wanted to know is, a buddy of mine gave me a dual tip muffler, and a high flow cat from a civic, both are new never used. but each is 3" openings, so, i was wondering if i could run duals into a single then into the cat and 1 3" pipe back to the dual tip muffler. would i lose power? just curious as the muffler and cat are free, if its decent i want to take advantage. plus i bought a cone, heatsheild and adapter, fuel filter spark plugs and wires, as this car sat for a year in a driveway, then i scooped it up for 100$ plus tow 7 miles. it runs and drives, but the powerbooster is shot, so no brakes. pedal is like a rock and does not move at all. otherwise it has a small hesitation, but i have yet to add new gas or change anything out. so let me know there fellaz, its starting to get chilly in jersey so im going to start getting this thing up and going before winter.
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1987 325iS, what more do you want for 100$? whats better than a shiny running/driving bimmer? -
The ideal homemade exhaust for your car has a y pipe just after the down pipes into a 2.5" single tube. Then into a cat or resonator(if you can delete the cat and get away with it = better performance & gas mileage). Then 2.5 all the way back to the performance muffler of your choice. 3" is somewhat on the large side and you will probably lose some low end torque without some back pressure. However, the cat might give you enough that you don't lose the bottom end. -
Yeah, i was hoping that the cat would regulate the loss of back pressure, but i guess you never know. Is there a site i could buy a y pipe from or do i need one made by a shop. Also, with it being a high flow cat, it shouldn't be to restrictive i don't think. i can get away with not having a cat, however, i would like to have the high flow on there. The mufflers not a great brand but it is brand new and decent, i had the same muffler on a car before and it sounded ok. Im going to pull the old exhaust off tonight because the cat or resonator has a huge hole in it, sounds ok though.1987 325iS, what more do you want for 100$? whats better than a shiny running/driving bimmer?Comment
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check summit racing for y pipesComment
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i found that magnaflow has a y for about 25$, what sucks is i have a 4mo baby and i pay for everything, and i get paid every 2 weeks, so im working off a 150$ budget every 2 weeks, i just basically want to get the exhaust and brakes done so i can atleast drive it through the winter and enjoy and save money up for mods in spring.1987 325iS, what more do you want for 100$? whats better than a shiny running/driving bimmer?Comment
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i'm going to use the magnaflow y pipe also, if you have a shop make you one it's going to cost 3x as muchComment
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I bought a Y exhaust tip and modified it to work $5, beat thatComment
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that'd be nice but i have no welder, so i still gotta pay somebody to weld it.1987 325iS, what more do you want for 100$? whats better than a shiny running/driving bimmer?Comment
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Are we STILL talking about "backpressure"?
I think the 'backpressure' concept was put to rest somewhere around 10 years ago. backpressure is NEVER good for an exhaust.
The 'thing' that makes too-large diameter exhausts suck is the impediment of flow due to cooling and increased turbulence, slowing the exhaust stream down.This is your M20 on steroids:
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