Go 3" and you will lose more bottom end. Heck keep going big you might as well add big valves/port the heads, and put a cam in that works from 2500 rpm and up. Bigger is not always better. Pipe can be bent so you can put the tip wherever you want.

 

You guys rock as always. I'll go with the 2.5 then.

Well thats the plan. It won't be until next summer though, I have to use my baby too much during winter.

 

When I went from stock exhaust, to no cat, 3" pipe front to back on my firebird, I gained a fair bit of low end. Of course, the TPI was specifically designed to work in the lower RPM range, just like the kegger on our trucks. (long runners.)

I don't think a 3" single will compromise bottom end noticeably. In this particular case, I think it is more a factor of the large primaries on the headers that is going to be the issue. Using the pacesetter y-pipe, should kinda fool the engine into thinking the collectors are MUCH longer than they really are, and contribute to good scavenging.... whether that will offset the larger than they should really be primaries or not.... anyones guess.

 

Thanks HeyYou...

If I can eek out a little distance between the Cat and muffler (guessing 12" max), I wonder if reducing the pipe size in this area would help?
I'll start out with 3", and if things don't decline from where I am now, I'll leave it be.

Anything else to offset the loss of bottom end?

 

Could install a chambered muffler.

 

I have the Hughes Airgap installed not the kegger

 

You can be certain than any aftermarket performance item for the 5.2/5.9 is built with the 5.9 in mind, not the 5.2... so the 5.2 users have to live with the overkill, unless they're willing to go custom built.