1987 N/A Exhaust Question

[AnubisMK3]

Ok so my whole exhaust system was setup for 2.5" throughput, however I have a brand new spun metal 3" Cat bnib that my friend mike picked up in exchange for some mustang parts (package deal). Anyway would i create a backpressure issue
if i opened the pipes and put in the 3". Main problem being in Wisconsin every shop I've talked to about leaving the Cat out gets pissy with me on the phone. I'd do it myself but I don't have a pipe bender, and honestly I'd rather do it on a lift.
So, do i have them install the exhaust from the cat back and put the cat delete pipe in myself, or hit up one of their shop guys for an "on the side, when the shop is closed" type job?

 

[MPR]

Just put the 3" cat on with a 3" to 2.5" reducer on each side to match your existing 2.5" exhaust piping. Will cause no issue with back pressure. No point in deleting the cat. Will barely gain any power and it's illegal (here anyways).

 

[Supra NA-T]

I deleted my cat and I regret it, shit is stupid loud. No cat plus straight piped 2.5" uggh

 

[AnubisMK3]

Im not gonna straight pipe it , I do have a muffler. I'll throw some couplers on it and put it in.

 

[AnubisMK3]

Quiet Zone put my exhaust on this morning, im absolutely blown away by the PRP muffler, i was hoping it wouldnt be crackling fart canny sounds, And when he fired it up and I heard the deep rumble and throatiness I just about crapped myself.

PrP i believe is since out of business, they made really nice performance mufflers for awhile, I believe it was Performance Racing Parts, but my grandma's husband came across 5-6 of them at the mustang swap meet
and picked them up for $25.00 each. I kinda wanted the tannabe look, but he let me have one of the mufflers free so i couldnt pass it up.