Modding the rear battery section for straight exhaust on R53...

[madsedan]

I know some people have done it using something like a Braille or Odyssey battery slightly protruding into the trunk and I'm considering it as well.
I mean I hardly put anything int he rear of my car now as it is and I'd rather save the weight and cost and put something like an R56 exhaust on the car rather than one going around the battery well.
I have enough basic race car fab experience that I'm comfortable cutting the stock floor, prepping it, and bolting/weathersealing an aluminum floor pan in its place.
The weight loss from the battery, sheet metal, and exhaust should be close to 50# or more off the car.
Anyone on here done it?

[SilverBeam]

A lot of after market exhaust options require the battery box to be removed, so there are quite a few MCSs running around with a relocated battery. Most people change out the battery for a super light option as well while they are down there. This is something I may consider doing as well, not so much for the exhaust, but because I have a sub box sitting over my battery compartment now and I'm horrified of when that day comes around when I have to remove everything to get to the battery. Easily going to break the hardboard we made the false floor out of. Plus, I'd probably level out the weight of the sub a bit with the job.

Here's a photo guide to taking out the battery box. It actually doesn't look hard to do:
http://www.northamericanmotoring.com/forums/2529167-post37.html

[MINIGURU]

Personally this isn't very good idea.

1 Your car will be CRAZY loud, I've done this to a couple customer cars, not a good idea.
2 Those lightweight batteries always seem to fail.
3 How many of us are really professional enough drivers to get a gain from saving 10 lbs??? And if you have a sunroof, get rid of it first it's 60lbs

[madsedan]

Well said, I will be tracking mine like I did my M3's so I MIGHT notice 10-20 pounds but probably won't. Can;t get rid of the sunroof on my daily driver, love it too much.
I'll go oneball so I can actually hear the exhaust and then fab up something with a magnaflow on one side or buy one of the aftermarket set-ups with one muffler.

[Partsman109]

I removed my battery box and replaced the stock battery with an Optima Red Top laid on it's side.
I am using the front resonator pipe from an R53 JCW exhaust mated to a stock R56 MCS muffler assembly.
It sounds perfect to me...not too loud and not too quiet.
http://www.motoringunderground.com/forum/showthread.php?t=15848

[KeysCoupe]

I changed to a Stebro catback system when My '03 was almost new. That aftermarket system was at least half the weight of the stock system, and it runs and sounds better to bootThat, along with a small battery, would be a great weight savings. I wouldn't cut the battery box out.
-Donny