Is a 4" exhaust actually large enough to make a difference? The reason I ask is I have a 4" echo tip (24" long) slipped over the stock 3.5" outlet. Looking at this, the 4" just doesn't look to be large enough to be worth installing?

I guess I am leaning towards a 5" custom system, especially since I am thinking of using two 5" tip out stacks. ;)

Any opinions one way or another?

I hear that the 5'' is mostly just for looks and it gives it a slightly deeper sound. I have not experienced this myself but its just what ive heard. If this exhaust system includes a new downpipe (3 1/2'' or 4'' i cant remember which the aftermarket systems come with) it definatly make the difference. And if your considering stacks get 5 or 6 inch!

I've been told from a reputable dealer here on the site that anything over 4" may actually hinder performance. 5" looks cool, but may just be too big. I guess that's why most real pullers use 4" systems.

I received the same advice about 4" versus 5". The 4" pipe already presents close tolerances and clearance issues, can't imagine the 5" makes it any easier. Couple of guys have posted a ringing sound at idle with the 5", likely contact vibration underneath. I like the 4" exhaust with 5" SS tips. Oh yea, cool duals to boot! JJ :)

Is a 4" exhaust actually large enough to make a difference? The reason I ask is I have a 4" echo tip (24" long) slipped over the stock 3.5" outlet. Looking at this, the 4" just doesn't look to be large enough to be worth installing?

I guess I am leaning towards a 5" custom system, especially since I am thinking of using two 5" tip out stacks. ;)

Any opinions one way or another?
You could do what I did. I custom made a 4" straight piped system all the way back and then put the dual 5" stacks up into the air. Let me know if you want pics.

I am getting a 5" full exhaust, straight piped next week, will let you know how it turns out..........

i have a 5" exhaust and i like it alot, i havent had any probems with it or any clearence issues

I have 4" on mine and it rubs the Rear shock and the spare tire as well so I don't know how you would ever get it out the back with 5" unless you go though the bed like most.