I am buying LT headers from pacesetter for my 97 4x4 4.6L in a few weeks. I am thinking I'll run an X-pipe and Flowmaster 40's behind the LT's. What do y'all think will sound best and give the best performance? I also have a CAI. Anyone know what power gains will be with and without a custom tune? Thanks.

 

I was looking at dual in/dual out mufflers with x pipes built into them. Might help you save money.

 

X pipes need to be as close to the front as possible. The mufflers with the X in them are for people from the "true duals" era that think a crossover is only semi useful.

OP: If you're looking for the best performance, you need to be looking at straight through mufflers instead of the chambered mufflers. Also without a custom tune and LT's, you run the risk of funky a/f ratios. Best to save up for the custom tune at the same time.

 

So if I put the LT's on my truck with the custom tune at the same time with the true dual setup I have with a straight through glass packs, is that the best way? I feel like that will be way too loud and offer no back pressure at all.

 

So thats why im still throwing a lean code... Ive got longtubes no cats x pipe and 2 magnaflows. I turned off my rear o2 sensors with my SCT and im still throwing a lean code. Im getting a custom tune after my 4.56s get installed so hopefully that'll take care of the code..

 

Was the power added a big difference. Do you like your setup?

 

So thats why im still throwing a lean code... Ive got longtubes no cats x pipe and 2 magnaflows. I turned off my rear o2 sensors with my SCT and im still throwing a lean code. Im getting a custom tune after my 4.56s get installed so hopefully that'll take care of the code..

 

Power increased a little bit but I wont see a big difference until I get the custom tune for the headers. The SCT gave me more power than the exhaust. Doesnt matter what kind of exhaust.u have, theres only so much power you can get from one. The more "free flowing" the better.

 

Read the link in my signature if you think you need backpressure. Put the LTs on, with a crossover, and duals along with the custom tune. Then use the straight through muffler of your choice. Personally I think your system would deserve something better than glasspacks. Look into Magnaflow or Dynomax. You can change your sound level with the muffler and not change performance. Don't expect crazy gains. 15 rwhp @ 4500 rpm is a solid gain for long tubes.

 

Any time you change the flow past the front O2 sensors you need to have it accounted for in tuning. I'm sure you know how O2 sensors monitor a/f ratios and talk with the MAF so I won't go into that. I would get a custom tune as soon as you can as running lean can burn valves. You should be able to adjust for gears in user adjustable options after you get your tune so no need to wait.