[jaylawgtp]

I have a 97 GTP, 180 T-stat, K&N CAI, Intense PCM Stage 1, Intense 3.4 pulley, Gatorback belt, 99+ Coolant Bottle, autolite 104s, PRJ Wires, Thrasher Shift kit, Tranny Cooler, Hurst Hit Shift Fluid, 17" TSW Eurace Wheels w/ Potenza Tires, TOG Headers with DEI Exhaust Wrap. My Plain is to do stainless Steel 3" piping, remove CAT, Resignator and U-Bend, go straight back to Y, and Dual MagnaFlow Mufflers, will these be OK now and with my new engine currently being built which will be well over 400 horses?

 

[spd98]

It should be fine though you could live with 2.5 after the y if you wanted to. I know of several s3 guys running a simular setup. Trust me on 1 thing GET A RESONATOR. If you don't the drone will be awful.

 

[MikeGS]

Trust me on 1 thing GET A RESONATOR. If you don't the drone will be awful.

I agree.
A straight-through glasspack like a Magnaflow does wonders, beware of the cheaper louvered glasspacks though, they add too much pressure drop to the system.

 

[RenoGTP]

3" pipe

I have 3" piping into 2.5 at the Y into Borla's. The drone is bad under 3k rpm's, especially climbing a hill at low rpm - vibrates the inside of the car. I put dual 3" resonator tips on which helped a little. After the 3k the drone goes away and the whine of the SC is over more prevalent.

 

[MikeGS]

...I put dual 3" resonator tips on which helped a little...

I'm not sure about the "resonator tips" I was thinking more of a conventional, single resonator after the CAT.

 

[load97]

I have the same setup, but no resonated tips, instead one reasonator in placef where the cat usually is. Not bad at all, but I might even go quieter for my own taste's.
-Scott

I have 3" piping into 2.5 at the Y into Borla's. The drone is bad under 3k rpm's, especially climbing a hill at low rpm - vibrates the inside of the car. I put dual 3" resonator tips on which helped a little. After the 3k the drone goes away and the whine of the SC is over more prevalent.

 

[RenoGTP]

res. tips

I have been considering removing the tips and cut/welding in a 3" res. after the cat. I was also told by the exhaust shop that the size of the muffler can play some with the amount of the drown/noise. I had originally bought the Borla cat. back, but saw the size of the pipe and took it back. Either way, at least these cars (3800) don't sound like a duck having it's guts pulled out like the most of the imports do.

 

[Guest]

if you look inside most resonators they are straight through and wont cause any backpressure. If you are really worried get a 3.5" one and 3" to 3.5" converters on each end.