I'm sure this subject has been addressed before, but I did a search and couldn't find exactly what I needed! I have a 95 SC400, and I was wondering if anyone has replaced the stock exhaust with straight through 2.75 or anything for that matter, straight through. I'm talking about taking everything out, coming straight dual pipes off of the headers, going right into twin mufflers and out. Any opinions, suggestions, or has anyone done this! Thank you in advance!!!

 

I know that those cars will respond well to exhaust mods since they come pretty plugged-up, but if you do go with too much straight pipe, the car will just sound like a Mustang with a Flowmaster exhaust.
Do a search for posts by JBrady, he has a late model ls with a decent exhaust on it that works very well.

 

well I did a dual 2.5" with no secondary cats/resonators on my 92sc300 before i turboed it and actually gained 11 rwhp.. didn't expect to gain anything really

 

2.75" is too big.
2.25 is ideal for tru-dual on a 4.0L V8 if you go bigger you may gain on top end but your car will be significantly sluggish below 2k rmp. Trust me you will not be happy
x-pipe will give you more of an even flow than just straight and separate plumbing for each of the headders.

I did and re-did my exhaust 4 times now because I was a jackass and stubborn.

1. removed 3 resonators
stock headders, stock cats, 2.5" piping, Y-pipe, and single 2.5" exhaust

2. stock headders, stock cats, 2.5" piping, X-pipe, dual 2.5" exhaust, can mufflers

3. stock headders, stock cats, 2.5" piping, X-pipe, dual 2.5" exhaust, restrictor to 2.25" offset mufflers

4. stock headders, stock cats, 2.25" restrictor, 2.5" piping, X-pipe, dual 2.5" exhaust, restrictor to 2.25" no mufflers, 3000gt style tips

If I had to do it all over I would (I would change headders, ceramic cats also but for arguments sake)
stock headders, stock cats, 2.25" piping, x-pipe, dual 2.25" exhaust, dual magnaflow.

That's the setup that many went with and it's tried, tested and true.