Got some money now in the bank, and looking possible for a new catback. I have a set of dyno don headers with his y pipe, along with a 3 inch catback with a 3 inch cutout right after the y pipe merges. I am debating if I should just leave it as is, or possible making it into a 3.5 inch or 4 inch exhaust. Would I notice much difference between a 3.5 or 4 inch as compared to my 3 inch with a cutout opened. If it won't make much difference, I think I would just leave it along and save myself 550 dollars. Any advice would be great.
My car on the dyno made 470 horse and 455 torque at the motor

 

I'm switching to 4" catback but i am also hooking up a 100 shot too. I have the xr276 cam and switching to a custom LE cam AND the 100 shot so...yeah imma need it.

 

That's really your call. What is your current catback? You can do the larger catback, but the muffler choices suck and really negate some of the gains from the larger system! I have the Mufflex 3.5" single outlet and use a Hooker Aerochamber. I had the Spintech at first. Went from 370 to 380rwhp by changing just the muffler. I still have a cutout and it's only worth 5rwhp now. Do not and I mean do not get the crossflow designed Mufflex system. Good luck!

 

I wish they made Hooker Aerochamber in 4" I have to stick with Magnaflow

 

Actually they do! With a little modification! The inlet and outlets of their mufflers have reducers. Basically use the #21509 muffler which have the 3.5" inlet/outlet and cut the reduced section off. Once these are cutoff you now have 4" inlets and outlets.

 

If your looking to upgrade, get true dual exhaust with either 2 1/4" or 2 1/2". I noticed a huge difference in power and torque and with having dual flow masters the sound is unmatched to any cat back system.

Eric

 

duals won't work very well with my shorties and that is to much work, when I would lose ground clearance that i cant afford to lose

 

of course somebody tells me this AFTER i went ahead and bought 4" Magnaflow

 

do you have dyno results or even better....timeslips to show the difference?

 

with the cutout closed I ran a best of 12.62 through the edelbrock 3 inch catback, with the cutout open I ran a 12.03. thats with a 1.59 60ft. I had bad tranny probs and I know I can get into the mid 11's