Phil IM356D posted:So the straight through mufflers in your opinion "sound" better?? At this point I just want the car to sound better.
Stan Galat, '05 IM, 2276, Nowhere, USA posted:I've used both-- I think what you want all depends on how aggressive you'd like it to sound.
The straight-through will sound more like the Borla, but at that point, unless the pipe curves inside or something, it's really just like a $15 glasspack. If you want rowdy, keep the cat and run a cherry-bomb.
So the multi chamber is less aggressive. Might be the way to go for the "gentleman's" Conv D.
Ok. When I got home from work today I removed the new header and packaged it up to send back to CA. I separated the down pipe from the cat. There was a "bung" in the down pipe. So I removed the O2 sensor just past the cat and plugged it into the down pipe. So now I have the first O2 sensor in the header and the second at the end of the down pipe. Hooked the header back to the engine. Plugged up the electrics to the O2 sensors. Fired it up. OMG is it loud. But it idles smooth and it rips when throttled. I think I know 2 things now. I think the car will run just fine with the second O2 sensor in the down pipe. And OMG I don't want a straight glass pack or a straight muffler. I need something that won't wake the neighbors. Used to have a Buell Thunderbolt fit with a glass pack. It was kind of like that but LOUDER!
Phil IM356D posted:I think the car will run just fine with the second O2 sensor in the down pipe.
The O2 sensor after the cat is only there as an emission control device to ensure the cat is working. In most cases, it's not doing anything to alter the actual operation of the engine. For some engines, it may be used to trim fuel slightly in order to extend the life of the cat, but that's it. With the cat removed, you will get a check engine light (if that matters to you), but it can take several warm-up cycles before the ECU will do so.
Thanks Justin. Would it be better to just leave the second O2 sensor for the cat disconnected?
Phil IM356D posted:Thanks Justin. Would it be better to just leave the second O2 sensor for the cat disconnected?
I'd leave it in place. Removing it would throw a CEL immediately and the bypass circuits you might use to get rid of the code for the missing cat typically need a working rear sensor anyway to help fool the ECU.
Thanks Justin. I guess I can live with a constant check engine light. Have ran the car twice and it has not come on yet. Just bought the pipe and Magnaflow muffler to hook everything up without the cat. Going to keep everything 2.5 inch OD. I guess if the car doesn't run well without the cat I can replace the cat, put the O2 sensor in its original position and install different pipe. I know I can get it hooked up with or without the cat. I really hate cats. 
Had the day off today so I decided to install exhaust. I wanted to do a center exhaust pipe but my straight 4 engine is so tall and low there was no room for another loop in the pipe particularly since it's all 2.5 inch pipe. So it exits the passenger side opposite from what it was. Single magnaflow 3 chamber 14 inch muffler. Since I hate cats, no cat. Everything is held together with clamps and suspended with 3 rubber hangers. I may get it welded and lose the clamps. Have had it running 5 or 6 times with no check engine light. I may venture out in the rain to see if I can notice any difference in performance. But who cares it sounds great.
Terrific!
Sounds good Phil.
That's a nice sound, Phil.
You're a man on a mission with that car.
Revs real nice Phil.
You'll need to drive it for at least 20 min to see if it throws a code.
Wow, that engine revs quickly. Sounds very nice.
It does rev quite at bit faster when the car is parked. If it would just stop raining maybe I could see if its quicker. I guess my concern is that I've traded low end torque for high end hp. Just looked out the window. Still pouring. 
Phil, it will interesting to hear how loud the new muffler is with the top up.
AA little back pressure helps with torque. Do boxer engines do well with an "H" or "X" pipe?
I think all V engines like a crossover pipe. It's not always practical tho. And Phil's is an L4 anyway.
Sounds good, man. Hope it stops raining soon.
I can't wait to hear how the shake down cruise goes. Looks and sounds snappy!
It finally stopped raining in SE VA. Took the car out for about 45 minutes. The exhaust just rips under hard acceleration. When I downshift there is a nice rumble. Is it faster? It sure sounds faster. When I placed the 260 hydrocam with the new ECU program a year ago the car was definitely faster. This is just the completion of the package. And after 45 minutes of spirited driving the check engine light never came on. There is no exhaust vibration. And during steady RPM cruising the exhaust is pretty quiet. I just want to thank everyone for the great advice. Keeping the Tri-Y headers and down pipe was great advice. And I think the 3 chamber Magnaflow was perfect. I think I've finally reach my engine's performance potential. I've tightened up the suspension and placed the BMW 320 brakes. Pretty darn nice. I bought the car used but I think I finally have made the car my own.
Good for you Phil, it sound good from here but must be way better in the flesh... .
Awesome!
Excellent, Phil!
Ok. So I finally got around to having the exhaust I built welded together. I also had my exhaust and the Tri-Y headers and down pipe ceramic coated black. I'm currently painting the heat shield satin black. I'll post some more pics and video when I get it back together in a few days.
Looks awesome, Phil.
Really nice, Phil. Well done.
Done. Thanks to Ed and Stan and everyone who pointed me in the right direction. I would have really screwed this up without this forum. Merry Christmas.
nice job... Merry Xmas
Boom.
Looking really nice! Merry Christmas!
