removal of mid-muffler

I have a 1977 450sl and am considering removing the mid-muffler/cataletic converter when I replace the rear muffler. Has any one done this? I am not concerned with emmissions because I am in the older than 20 year exception. Also, has anyone compared OEM mufflers to any "performance" muffler to see if it did anything more than make more noise?

KAD
1977 450 sl
18" Lorenser wheels
Holly air filter
Bilstein shocks

[4NDELIT]

I don't know what it'll sound like, but I hope to tell you soon I plan on removing my middle muffler after I get it smogged [soon]

4ndlit did you ever remove that mid muffler? If so, what happened?

KAD

[4NDELIT]

I never ended up doing it... a combonation of parents and shortage of cash kept me back (I'm a college student living at home)

[jr811]

I replaced my cat. years ago with a stright pipe. Not much difference in sound. Performance seems better.

jr811,

Did you do this yourself or did you have a shop do it for you? Was this simple or complicated?

KAD

[txstinger]

I removed the pre-cats and mid muffler, enlarge the exhaust tube to 3", installed high flow cat and mild rear muffler.

I gained about 9 hp and lost a little low end torque. However, in the power band around 3200 rpm she starts to breath and I can feel it in the seat.

[tecqboy]

Every IC engine ( even Mercedes ) is designed ( read that tuned ) to operate into a certain about of back pressure provided by the exhaust system. A common assumption is that reducing the back pressure and allowing the engine to "breathe" more freely will increase performance. This is not always what happens. You may end up de-tuning the system and lowering the performance. I've no actual experience with Mercedes engines, but I do know that their exhaust is already highly tuned as stock. I do have experience on American performance and racing cars and I've seen the dynanometer tests results which show that the proper amount of back pressure increases HP. I wouldn't argue that replacing a plugged cat with a pipe is better than a plugged cat. But I think you ought to post the ? in the performance catagory and see if there is any advice there.

[txstinger]

That was my trade off. Less back pressure = less low-end torque.

The SL was tuned very nicely stock. The shop installing my exhaust was impressed. He said the only true gain for the dollar was in taking out the pre-cats & installing a higher flowing main cat.

I did not care as much on the lower end torque (MY SL starts off in 1st gear) as the gain on top end of curve.

All that said, if your car starts off in 2nd gear and tuning is out at all, the loss of low-end torque would be very noticeable.