I just installed megan long tube headers on my 06 350z NA with stock catback.

Some modifications:
kinetix ssv intake
jwt pop charger
manley connecting rods
cp pistons
acl main and rod bearings
Zex nitrous

After installing the long tube headers on my stock exhaust it seems
my car reacts slower. Normally the tires spins on the 1st, 2nd and 3rd gear.
But not anymore. i haven't G-tech the car yet but is feels it's slower now.
Any idea what to do?
Remove the big exhaust box at the end?

 

kind of weird. Idk how deleting the cats would "Slow u down". I guess get the Gtech out and get an approximate reading lol. Btw why do u have aftermarket rods pistons and bearings with stock exhaust? Not like they have relation but i wouldnt do them until i "needed" 2

 

The muffler?

 

Why do you have all that and your stock exhaust? Lol

Get an aftermarket exhaust?

 

lol u deff need an exhaust

 

Has this vehicle been tuned?

 

get an exhaust and tune....the de Y pipe is the worlds shittiest y, especially after you have opened up the front like that