Input on 4.8 resonator replacement options?

[Teutonaddict]

Hey, all-

I've done a search and read Articles about resonator removal, DanDE's resonator replacement, and another's MagnaFlow X-pipe install on 4.6/4.8.

I removed the factory resonators on my E39 M5 and replaced with a SuperSprint cat-back x-pipe and exhaust and liked that system very much. Pre/post dyno runs showed no TQ loss and slight HP gains from the S62 motor.

How do these options compare on the 4.8? I'm speaking strictly of resonator replacement/removal and not a full aftermarket system. Must be discreet in my modding of this particular Beast.

Can some of you with first-hand experience describe (a) what you did, (b) its effect on exhaust note, and (c) any discernible impact on performance?

Just so you know, I'm only seeking a more authoritative exhaust note and do not expect any performance gains from any post-OBD I powerplants. What I want to avoid, however, are any unintended performance penalties.

Thanks for your help. I'll post a full report with whatever I do.
-Dave

[ekaz]

I removed the resonator and replaced with straight pipe, not noticeable loss of power, huge difference in exhaust note. The X-pipe option quiets t down a bit. Not sure but maybe replacing with a high-flow muffler?

[X5Jay]

You can check out my little X-Pipe review here...

[Teutonaddict]

Originally Posted by ekaz

I removed the resonator and replaced with straight pipe, not noticeable loss of power, huge difference in exhaust note. The X-pipe option quiets t down a bit. Not sure but maybe replacing with a high-flow muffler?

Thanks, ekaz! I do think the resonator is the culprit here, as from that point back is pretty large diameter, low restriction plumbing. It's amazing what the factory does these days on our exhaust systems.

When you mention the X-pipe quieting it down a bit, did you mean relative to your straight pipe option, or relative to stock?

I think DanDE's 4.6 example was a higher-flow resonator replacement from one of the performance outfits. I'm still looking into that...

[Teutonaddict]

Originally Posted by X5Jay

You can check out my little X-Pipe review here...

I found your review earlier when ekaz referred another exhaust question to it. I've got the x-pipe part printed out on my desk.

Do you know of any 4.8 owners that went the x-pipe route?

I'm not sure that the differences are material, but it would put me at ease before taking the plunge. After all, we learned that the headers on my former M5 were exactly the same as those on the E39 540i. So in that case, what you did downstream of the restricted factory headers had limited impact on uncorking any more scoot. Did sound a heckuva lot better, tho'!

-Dave

[ekaz]

Originally Posted by Teutonaddict

When you mention the X-pipe quieting it down a bit, did you mean relative to your straight pipe option, or relative to stock?
..

Relative to my straight pipe option.

[asawadude]

Dave -

I think you're going to find that a cross section of owners here (3.0i, 4.4i, and 4.6is/4.8is owners who went both routes using either straight pipes or X-pipes. Do a search on X-pipes, straight pipes, or resonators and a bunch of forum messages will pop up. Everyone seems to be generally satisfied with what they did, regardless of which mod they picked.

From what I gleaned out of the boards, the straight through pipes are louder, throatier, but have a tendency to burble and pop on decel which some people like and others don't like. They also have a tendency to have a slight pinging or rattling sound when cold, but the sound goes away when the pipes warm up.

The x-pipe increases the sound factor, but not as much as the straight through pipes. The X-pipes provide a small amount of additional back pressure which helps minimize torque loss, but it's mostly negligble. The burbles and pops are minimal or gone completely with the X-pipes.

Horsepower gains are negligble with either solution, although some owners have reported a seat of the pants feel of more HP. However, everyone has reported a definite auditory improvement at high revs, but mostly outside of the car. The increased sound level of either solution doesn't intrude on the sanctity of the passenger compartment.

The exhaust note of the BMW engine can be like angels singing, but unfortunately the BMW designers didn't quite understand that until recently. BMW's current vehicles have a far better sound than before.

$150 parts and labor seems to be a good target price for either solution.

In either case, both solutions are better than the stock setup. It's an owner preference thing. Don't expect any major HP gains with this mod.

(Other members, please correct me if I mis-stated anything here).

Regards, Mike

[TQ2K]

Go for the X-Pipe option to reduce backpressure and a more civilized exhaust note compared to the stright pipe. Boils down to preferrence really.

[Teutonaddict]

Thanks for all the responses, folks-

Now I need some specific clarification. From using the search function, it appears that the 4.4 uses a 2.25" pipe (x or straight), while the 4.8 might use a 2.5" diameter pipe.

Can anyone with direct experience confirm that the 4.8 has larger diameter stock pipes (2.5") than the 4.4's?

Thanks for the help!

-Dave