Question about the quality of this exhaust

[TheWizardofOz]

I was looking around at different catback exhaust systems, and was about to decide on a flowmaster american thunder, but then I came across this: http://www.macautoparts.net/Exhaust-...oductInfo.aspx
It is a Dynomax catback, and only costs $200. After looking through the ad, I noticed that it was 2.5 inch in, and only 2.25 inch out. That sounded bad to me at first, but after doing the math, two 2.25 inch pipes out still has about 60ish% more cross sectional area than the input of the single 2.5 inch pipe.
1) Is this conclusion wrong or is there more to exhaust theory than I thought?
2)Is there anything else that should make me wary of buying this system from Mac Auto Parts?
3) Is there anything else someone wishes to enlighten me on?

Thanks in advance,
Mike

[flamingchicken]

Re: Question about the quality of this exhaust

it looks good to me. But on this site you will have TONS of people against the 2.5 and for the 3". i for one am for 2.5". My system is 2.5 from the headers back, to two 2.5 exits.

[TheWizardofOz]

Re: Question about the quality of this exhaust

Thanks for the quick reply, and I have seen the many debates on 2.5 versus 3 inch, but there are so many non-fact based arguments that I have been unable to find if there is a noticeable gain in 3 inch unless you are using a power adder, which I am not. I have a 2000 and from reading sticky's that means I have 3 inch to the cat, and currently 2.25 out from there. I've also had my cat replaced, and I'll have to check by getting under the car, but I believe my new cat is 2.5 out and then to a reducer. Will this make the installation go smoother or more troublesome? Thanks again.

[flamingchicken]

Re: Question about the quality of this exhaust

not really. it all depends on if they changed the s-pipe when they changed the cat, or if you get an s-pipe in the new kit. If you dont get an s-pipe in the new kit and they didnt change the old one out, then you will have 3" into the cat, 2.5" out reduced to 2.25" s-pipe, then the new cat back will be from there back. So the cat back wont really help unless you get the increased size s-pipe, which does not look like its included.

[TheWizardofOz]

Re: Question about the quality of this exhaust

Ah yes, I knew about that but forgot, because the S-pipe seems to come with some systems but not others. I'm sorry if this is a stupid question, but I want to double check. An ls1 exhaust will fit with hanger modifications, correct?

[flamingchicken]

Re: Question about the quality of this exhaust

that i cant tell you. i would believe so...i had my exhaust custom made from a shop around here. The guy did an awesome job.

[cam98aro]

Re: Question about the quality of this exhaust

Ah yes, I knew about that but forgot, because the S-pipe seems to come with some systems but not others. I'm sorry if this is a stupid question, but I want to double check. An ls1 exhaust will fit with hanger modifications, correct?

yes.. that is the way i would go personally..

i bought a duel exhaust from a forum member, it was from a 97 y87 car i believe.

i had to mod the hangers a bit, but it worked fine, i get the look of dual exhaust, without the annoying ricer sound.. best of both worlds