Magnaflow high flow cat

[PT's VIBE]

I haven't posted here yet but I have been an observer for some time now. i am thinking about installing a high flow cat on a 03 GT and wanted to know if anybody else had done this?if so how well did they work out and what part numbers did you use from Magnaflow for the installs? i currently have the Mag CB exhaust now.Thx in advance for your help.

[drunkenmaxx]

FYI, a high flow cat has only been shown to net like 1hp, so unless you need to replace the OEM, i wouldn't bother.

[PT's VIBE]

DOH well if that's the case I'll just leave it alone then till I need to change it then.Thx for the info.

[Petrucci914]

I had Magnaflow cats installed last week on my Base. They made a big difference but I think something was up with my stock cats. I'm also running FI with a header, so I was really pushing out a lot of exhaust quickly. So unless your cats are bad, or you're running FI, it's not really necessary at this point.

[PT's VIBE]

The reason I was kicking around the idea is because I will be installing a DC Header and thought that might be a good time to add that to the list. I only have about 40K miles now on the car so I don't know if it will really be necessary (but what is when you modding)

[Petrucci914]

If you're going to do it, I'd do it after you have your header AND Catback exhaust. The reason I say this is because of the weird inlet/outlet size on the cats. The pre-cat has a 2.25" inlet and outlet. The post-cat has a 2.25 inlet and a 2" outlet. If you get the catback exhaust it is 2.25" the whole way. Then when you have that you can purchase two cats that have the 2.25 inlet and outlet. Hope that makes sense.

[PT's VIBE]

I currently own the Mag CB exhaust so I'm pretty sure that it's 2.25 from start to finsish.

[Petrucci914]

The Catback is, yes, but the portion between the catback and the last cat is 2". That is how you were able to clamp the Catback over the stock pipe. So with your setup you can do the 2.25' converters if you want, they'll just weld a 2.25 pipe after the last cut and weld it to the catback so you won't need the clamp anymore.

[PT's VIBE]

OK I think got it now the light bulb over my head just turned on. Thx

[ProtonXX]

The JP midpipe I put on my car made a big difference. Somewhere above CAI but below the Alt & Crank Pulleys

[1zzfe_808]

alt and crank pulley made more HP for you than an intake?