I thought I would put this together for those that hate the way their aftermarket exhaust sits under the bumper.

It's very easy to do, only took me about 30 minutes, but realize that you are working on a finished surface. It's not that hard, but if you are uncertain of your ability to do this, you probably shouldn't. Otherwise, take your time and move slow. A small mistake can f* up your paint, or make your bumper look all hacked up. Besides, cutting slow more than makes up for itself in time saved sanding.

To start, I have practically every cutting tool you can imagine (power and hand). It's NOT WORTH TRYING TO USE A POWER TOOL. Power tools only help productivity and speed, unless your going to spend an hour making a proper jig so you can cut ten bumpers, just cut it by hand.

You will need:
- Coping saw ($5.00 at any harware store)
- Masking tape (blue or green so it doesn't leave residue)
- A sharp pencil.
- Cardboard
- Your exhaust tip (can be attached to the car.. but it may make it difficult. You may want to unhook a hanger to clear up some room)
- Sanding block or small block of wood
- 80, 120-150, and 220 grit sand paper.
- Patience.


Start by lining your tip up against the cardboard and tracing an outline. Then transfer lines to leave at least 1/2" gap around the tip (1/2" looks bigger on cardboard than it is on the car.. mine is 1/2" for reference inthe pics).
http://i13.photobucket.com/albums/a272/Biscuitsnotdead/exhaust%20cutout/1pattern.jpg


Then cut out said cardboard pattern.
http://i13.photobucket.com/albums/a272/Biscuitsnotdead/exhaust%20cutout/2cutpattern.jpg


Almost forgot to take this photo, but mask off your work area with blue or green masking tape. Then mark reference orientation marks where you would like the tip to end up visually. Pointer 'V's or Arrows help to locate your marks when they are covered by your pattern.

I scribed a line 1/4" down from the valence seam to align my pattern against. This will keep the tip square with the panel and not look all cock-eye'd and stuff.

Line up your pattern, trace the line with a sharp pencil, stand back and inspect. Take your time here. I stacked up a couple of shoeboxes to mock-up my tip beneath my bumper.

http://i13.photobucket.com/albums/a272/Biscuitsnotdead/exhaust%20cutout/3tracepattern.jpg


Before you start cutting, orient yourself with your Coping saw.
http://i13.photobucket.com/albums/a272/Biscuitsnotdead/exhaust%20cutout/4copingsaw.jpg

The teeth have a 'cutting' direction and a 'relief' direction. You want to minimize the risk of "chip-out", which is where the teeth chip/pull paint from the surface. Automotive paint is pretty durable, but it's better safe than sorry. This means you will probably need to flip the blade around in the saw to allow you to cut in the proper direction.
http://i13.photobucket.com/albums/a272/Biscuitsnotdead/exhaust%20cutout/5blade.jpg

Coping saws are also cool because you can rotate the blade as you cut. Meaning one continuous cut, no seams, less sanding, better finished product.


Start your cut, again, cutting AWAY FROM YOU. When you pull the saw towards you, only apply medium pressure to avoid chip-out.
http://i13.photobucket.com/albums/a272/Biscuitsnotdead/exhaust%20cutout/6cutting.jpg

You may or may not need this:
http://i13.photobucket.com/albums/a272/Biscuitsnotdead/exhaust%20cutout/7heatshield.jpg


Once cut, use a sanding block with 80 grit to straighten the strait parts. If you took your time, this should be easy. Fold some 120 grit around your fingers and work on the curves.
http://i13.photobucket.com/albums/a272/Biscuitsnotdead/exhaust%20cutout/8sanding.jpg

It's all in the details:
http://i13.photobucket.com/albums/a272/Biscuitsnotdead/exhaust%20cutout/9corner.jpg

Take your time.
http://i13.photobucket.com/albums/a272/Biscuitsnotdead/exhaust%20cutout/10cutout.jpg

http://i13.photobucket.com/albums/a272/Biscuitsnotdead/exhaust%20cutout/11end.jpg


Finished product:
http://i13.photobucket.com/albums/a272/Biscuitsnotdead/exhaust%20cutout/12poop.jpg

http://i13.photobucket.com/albums/a272/Biscuitsnotdead/exhaust%20cutout/13poop.jpg

Have fun!

Nice DIY.

looks good biscuit. great write up!

I think it looks perfect. Great job!!!!

looks really nice sine im afraid to hack into my e39 im getting it done at a body shop next week. cutting my bumper is almost like giving myself a flu shot.

Very nice writeup. Great technique and I appreciate how you explained the reasons behind much of what you did.

I have a suggestion: You took a lot of (good) precautions to prevent paint chipping. If you want to take the post-protection a bit further, you can apply touch-up paint to the exposed edges of the cut. That will keep the paint sealed and will hide the grey plastic edge and make it that much more professional-looking. This is one of the final steps taken when one cuts the sheet metal on 96-00 cars to accommodate the 2001+ tail lights.

Other than that, great technique and nice license plate!

Very nice writeup. Great technique and I appreciate how you explained the reasons behind much of what you did.

I have a suggestion: You took a lot of (good) precautions to prevent paint chipping. If you want to take the post-protection a bit further, you can apply touch-up paint to the exposed edges of the cut. That will keep the paint sealed and will hide the grey plastic edge and make it that much more professional-looking. This is one of the final steps taken when one cuts the sheet metal on 96-00 cars to accommodate the 2001+ tail lights.

Other than that, great technique and nice license plate!

I honestly thought about it. If it were metal there is no way I wouldn't do it. But you really can't see the black edge in person unless your really looking. And it kinda ties in with my black trim. It's sanded and polished so that if you didn't know otherwise, you would think it was oem.

If I had a white or silver car, it might be more noticable. But for now I just don't think it's worth it.

Glad you like my vanity plates :)

fantastic diy project,those pipes, realy look cool comeing out the back of your 39, ill be doing this job myself .

Looks great may i ask what muffler your using?

no muffler actually. Just the factory resonator and a straight pipe.

Sounds fantastic, and not as loud as you would think. Can hardly hear it in the car. I could easily add a muffler later, but my shop recommended i try it without it first. Saved me $ too.

I just did this on mr 540i for my Dinan exhaust. The cutout portion was easier than I thought. Ill post some picks when I get it back from the shop.

I guess I cant post pics yet, but I love it. It worked great. My dinan is alot quieter than I thought though. I think Ill be taking out the resonator.

Mufflers break in a little. Give it a few weeks before you change anything.

I'd be a little nervous about using a coping saw just because I think i'd be awkward to handle. Here is a write-up we did last year that has a nice PDF to save to your computer and templates.

http://forums.bimmerforums.com/forum/showthread.php?t=682844