Straight Pipe Fun

Well, I finally got around to going to the exhaust shop today. I had them replace everything from the downpipe back with 2.5" pipe. First impressions are...

1. It's loud
2. It sounds awesome
3. No more dead spot in the upper RPMs... especially noticable on the highway... it pulls from 70 - 110 mph much faster now. Sorry, I don't have before and after times.
4. Quicker turbo response.

The oxidation catalyst or whatever was about 20% plugged with soot. I didn't cut the pipe off of the resonator or the muffler to see what kind of shape they were in, although the muffler was developing a hole in it and was starting to make rattling noises from the inside.

That's it for tonight. We'll see if I can avoid being pulled over for excessive noice in the morning.

[ned2683]

i had 2 set up of straight pipes on my car

1. cut off at center - very loud can hear turbo spool

2. and normal straight pipe to the rear- not as loud, same tone, no turbo spool.

no.1 was awesome, but at cruising speed it gets really old really quick. and u can't hear as much sound out of the cd player.

The 603 is still very quiet cruising down the highway at 60 - 70 mph... only a bit louder than it was before. It really starts to bellow if you step on the loud pedal though. It's accelerating from stoplights in the city that is a bit obnoxious. I'll have to see how much it irritates me and other people... I may end up putting a resonator on it. It's still too soon to tell.

[SYRacing]

I think the stock exhaust pipe is metric..i know on my 123 the exhaust pipe is very close to the transmission and to the right hand side of the firewall as its dropping down..I'd love to put 3 inch on mine with no muffler
I'm trying to save my pennies.....lol

Well, parking garages are interesting. Alarms chirp when I drive by and the echo is incredible. I'm beginning to think about some sort of high-flow muffler just to knock down the dB level a little bit.

Ideally, a 2.5" mandrel bent system would probably be the best. Too bad my exhaust shop guy doesn't have $100K to plunk down on a mandrel bender and the tooling.

Originally Posted by SYRacing

I'd love to put 3 inch on mine with no muffler

A buddy of mine put a 3" system on his '83 300D and it was obnoxious. It sounded good, but it was too loud for around-town driving. He ended up installing a muffler after about a week.

[OhioSDL]

veedub,
I also went with a 2.5" mandrel bent exhaust but I added a Flow Master muffler.
I really pleased with the sound. It has a sort of deep rumble. It like a big v-8 but with a little less "burble" probably because of turbo and being a 6 cyl.
The constructions of the mufflers are awesome. Thick aluminized steel. (Stainless is available) and it has no dampening material inside to get clogged with soot like cheepies.
I called several manufacturers before I decided on flow master. Their techs were very helpful in the size selection. The model 50 that I went with they say is being used on the local school systems school busses. But check out their website
http://www.flowmastermufflers.com/cgi-bin/flowmaster/50series.html?id=j8vUpb6e

My thread on my experience on the installation and the part numbers of what I ordered.
http://www.peachparts.com/shopforum/showthread.php?t=92877

In hindsight. I would have liked to have a custom job to get a closer fit around the rear shaft and moved the muffler location to the original muffler location as having mounted it in the resonator spot has dropped my clearance by about an inch. Ive only scraped it 2-3 times but that muffler is still looking great. I would really have to nail it to even scratch it. I am quite pleased with this product and when I have to get new exhaust for my Toyota Tacoma, I plan to use their parts.

[SYRacing]

Originally Posted by VeeDubTDI

A buddy of mine put a 3" system on his '83 300D and it was obnoxious. It sounded good, but it was too loud for around-town driving. He ended up installing a muffler after about a week.

Could you hear the turbo spool up even more? I've got a custom intake, and it sounds like a freightliner
Makes me want to push the pedal down even more!!

I'm curious though.....was it 3 inch from the downpipe or was it a COMPLETE 3 inch system from the rear of the turbo to the rear of the car?

[Gurkha]

Having bone to a fresh air intake and straight pipe, my throttle response bettered and so did my acceleration, specially top end one, not to mention my mpg has gone up significantly and so did my operating temps. The sound now is way sweeter than the muted civlized one I had before, people pay respect even though it is a diesel. I can hear the turbo spool especially when I am de-accelerating and sweet whistle at high rpm.

I did this last year and have never looked back. My engine is the OM616 turbo.

[SYRacing]

well of course people pay respect
ALDA is maxed on mine, it bellows a bit of black smoke
EGTs will probably drop once the piping is complete on mine as well....

[Gurkha]

Originally Posted by SYRacing

well of course people pay respect
ALDA is maxed on mine, it bellows a bit of black smoke
EGTs will probably drop once the piping is complete on mine as well....

No ALDA on mine, all mechanical IP supposedly doesn't need one, no black smoke either and the fresh air induction has actually lowered the emissions.

[Dee8go]

Originally Posted by VeeDubTDI

Well, parking garages are interesting. Alarms chirp when I drive by and the echo is incredible. I'm beginning to think about some sort of high-flow muffler just to knock down the dB level a little bit.(

Vee, isn't it illegal to drive a car with no muffler of any kind? Flowmasters seem loud enough to satisfy the need for a deep, throaty exhaust sound. They also reduce back pressure and boost speed. I'm wondering what the maximum diameter restrictions are for exhaust pipes. It seems like 3" would be a lot tougher to accommodate.

[TheDon]

what ya do is keep the stock system go out and buy one of those exhaust outlet valves they sell in the runer mags and run a 2.5 inch pipe out the side by the rear wheel... put the outlet valves right off the downpipe.. when its closed its going through the stock system when open it closes off the stock system and switches to straight pipe..

Originally Posted by Dee8go

Vee, isn't it illegal to drive a car with no muffler of any kind?

I've had no issues in 3 years, even during emissions testing.

[ConnClark]

With a turbo, mufflers don't need to muffle as much because the turbo converts some of the pulse energy to useful work. It depends on the state law. In Washington state the law says (or at least it used to say) that all vehicles have to have a muffler. That included electric cars too, its just that it isn't enforced on electric cars.

Depending on how the law defines a muffler, one might even be able to argue successfully that a turbo is a muffler providing the car isn't excessivly loud. I know for sure I can argue that my Oxidation Cat is a muffler because it baffles the pulses and provides for expansion. If the car isn't too loud and you get called on it go to a junkyard and get a resonator off something and tell them its a muffler. They would have to cut it open to prove it isn't.

Edit : Note, exhaust bypass valves aren't legal in some states either.