To much exhaust?

[akalt24]

I dont thank I have asked this before. I have 00 sport ls 3.0 2wd.
Back when I was younger I had muff cut off and had 2 1/2 from there to a y pipe to have streight dual 5 inch tips. Is this to much exhaust and could i be loseing performance from this? I have a k&n filter but need a real intake. Do i need more back pressure now with the stock intake?

also i have question from the engine manifold pipes into one what is next inline before the cat converter? I see the cat but between it and wher the manifold pipes join is something im not a car guy i dont know esactly what it is has like braided wire look to it what is it? I wish I had a factory service manule

[DSM]

it's a flex section, they're prone to leaking. 2.5in would be fine for exhaust, might be a little loud and raspy, i'd suggest 2.5 with a decent muffler or 2.25 if you really want straight pipes.

[cwic]

if u open up the exhaust and not the intake to build the back press up u will loose some low end torque but gain some top end hp.
clay