I was wondering that myself.

 

I was hoping the turbo would spool up quicker. No such luck. It did pull harder once it got going. The muffler seemed to take away some power, but not as much as I gained from the gutted cats.

 

It was on 5psi. I ran 10psi last friday on an 1/8 mile track and went 8.29 with a 193 60ft. The mph wasn't working so I dont know how fast I was going. I still have some tuning to do on it. Hoping to get it in the 7's soon. The times on 5psi were on street tires. The 8.29 was on DR.

 

I may dyno mine this weekend. If I do I will post it and see what kind of difference it made.

 

Note to self......keep the factory cats!!!

I'm running factory cats and a simple y-pipe to "fake" duals out the back. The sound level is just about right. Any louder and it might be too loud, but it's nice and burbly sounding.

Does anyone have proven dyno gains by gutting or removing the cats? I'm putting down some serious power with stock cats. I can't imagine it would bet that much more?.?

 

So a muffler BEFORE the turbo helped it spool faster? How much faster? I'd like my 4.8 to spool a little quicker, I bought a .69 A/R exhaust housing to try to bring it down a little bit, but would be nice to spool it around 22-2500 instead of 3K. Did it help the air rush noise when the waste gate was opened? I love the whistle noise from the turbo, but the air rush noise leaves something to be desired.

 

I think he meant he put a muffler after the turbo.

After the turbo it really quiets the wastegate noise if you still have it plumbed behind the turbo and into the tail pipe. I have noticed that my truck feels better at part throttle with the muffler on but I have never measured spool time on or off.

 

Mine is just before the turbo. I can't tell any difference in spool time. It does have more power than with the cats though.

 

My bad. Do you have pics?? I thought about doing that to reduce motor noise but keep the spooling sound of the turbo. Is that how it worked for you?

 

Sorry no pics. They did a really nice job. Cut the old exhaust off at the flange that bolts to the turbo. Mandrel bent a new 3 inch pipe and welded it to the flange. Cut off and welded the tube and flange to the waste gate. Now I have 3 inch piping from the y-pipe to the turbo with 3 inch inlet and outlet magnaflow. And, 3 inch tubing from the turbo back. It did reduce the engine noise a good bit. Unfortunately it reduced the spooling noise, but not by much. It used to whistle really nice when you eased into the gas. Now you can barely hear the whistle. I need to let someone else drive by in the truck so I can hear what it sounds like. Before at the track everyone said all they could hear when I went down the track was the turbo. From inside the truck the only thing I could hear was the exhaust.