Hey everyone!

Just wanted some quick input about a delimma I've hit. As soon as the might wallet permits, I will be installing a 98-99 Vortec 5.7L V8 into my '91 XJ. I love the fact that the stock 330 lb ft of torque hits near 3k rpm (can you say awesome 4x4 ability?), and the stock 255 hp will be easily bumped up to about 300 hp with upgrades I have in mind. All while getting at least my stock 20 mpg, maybe slightly more considering the big 5000 pound Tahoes can squeeze 19 mpg highway sometimes. Anyways, here is my delimma.... Should I run duals out the back, or stick with a single outlet in the stock location?

I won't be running true duals, but what I was thinking was having the two 2.x inch collectors from the headers collect into a 3 inch pipe, run that pipe through a 3 inch High Flow cat, then to a 3 inch Flowmaster Super 44, but the Flowmaster I'd get would have the 2.5" dual outlets, which I would then run dual pipes out of. Otherwise, I'd use the same setup, just with one outlet.

Which direction do ya'll think I should go? I know the stock Vortec heads have an exhaust port that can be slightly choking, but at the same time, I don't want my rig to sound like crap or kill my exhaust velocity and cause all sorts of turbulance.

Side Note -- *** PLEASE don't pipe in on here and start rambling off on how "I can build a stroker for less" or "Use an LSx Engine". First off, I have NO DESIRE to deal with a stroker. I've heard and seen my fair share of their failures. As for the LSx engine, the LS may be superior to the Vortec L31 in terms of modern upgrades and power, however even the LSx can't argue with the Vortec L31's torque curve and peak. Plus, LSx engines around here are rarer than Elvis sitings. Thanks! ***

 

Haha, I'd like to drive an xj with that much nut, that would be fun. As for your question, dualies got a nice sound to em, so that's my vote.

 

Run two would sound sick

 

Since you're already going down to one pipe there's no reason to then go duals later other than looks. That and XJ's just look kinda funky with duals IMO. I say single pipe it.

 

Agreed.

 

single pipe. make a good sleeper

 

Lol I find it funny how the poll is tied. In all honesty, I guess my main goal behind the duals was opening the exhaust a bit. Do you all think that 3" is enough to let the L31 breathe? I mean, I've listened to stock 4.0's with dual outlets on a Flowmaster, and honestly I think my single outlet 2.5" flowmaster sounds louder... maybe it's pushing more flow in one direction rather than splitting it. But thats with an I6... Idk if duals out back for a V8 are of any benefit or have specific tone.

 

Single.Inline not a V format. enough said.

 

Single 3" you'd be suprised how good it sounds, I did a single 3" on my 1987 Crown Vic Wagon, along with a host of other things, and people always though it sounded great.

 

Does it flow well?

 

duals belong on a v8, and should be "true" duals

 

Agreed. If you're gonna do dials, do it right or not at all. A good set of tuned headers (if you could even fit them) would do you good.

 

There's only one set of headers that work with these swaps and the mounts that are used, and thats these guys right here:

http://www.novak-adapt.com/catalog/h...v8_headers.htm

 

I kinda figured they would be somethin along those lines. Those are pretty popular, even in the full size chevy world.

 

It flowed well enough for 400 horses out of a 302.... and it flows well enough for most OEM's to use it or 3 1/2" stock on a lot of vehicles including some Vette's, if you do duals use some type os crossover either an X or H-pipe or you are wasting your time.