car feels sluggish after longtube install plus tick tick tick noise

at first my car felt great and it still kinda does but at 40-50 it seems it has a flat spot or slight hesitation, what is this and will a pcm tune correct this? and im still getting a noise its like a ticking noise, usually at idle you can hear it good, when i pop the hood its not too loud but when i lay under the car by the y pipe its very noticeable, i cant seem to fund a leak in the system anywhere.

The ticking is an exhaust leak.

Track it down, because they can rob HP.

Did you do the AIR mod when installing the headers? If not, the AIR system will cause a ticking noise. IIRC, Basically all you do is make a blockoff plate and drill a small hole in it. Not sure on the size because I just went !AIR with my headers.

Also, did you rest your PCM after the install so it will relearn?

yes i did the air restrictor mod the directions said drill a 3/16 hole in the middle and 5/16 for the bolt holes but the person who wrote them was way off because 5/16 drill bit was way too small for the bolt holes for the middle on ei used a little bigger than 3/16 but the hole is still very small, when i put my head by the air the sound isnt very noticeable but down by the y pipe it sure is. i guess i will try taking band clamps off and putting silicone on them and putting them back on to seal it. wonder if i should let the silicone dry for 24 hours or if i could start the car and go??

my catalytic converters clicked like a mofo, so I took them off. Bottom out too many times and you'll loosen up the materials inside and they'll click. but more than likely you've got a bit of a leak... also, make sure your plug wires are all secure. If it's arcing they tend to click very loud.

i dont have stock cats i have jethot cats in the y pipe

And exhaust leak will let outside air in to the O2s and throw the mixture off. Find the leak and fix it.
If you do use sillycone make sure it's the sensor safe type or you'll end up buying new O2 sensors.