any thoughts or opinions? i live in vegas and all the muffler shops say they do compression bent and said mandrel bent is way more expensive. what you guys think?

 

For an NA engine, its not a big deal and probably a more cost worthy buy.

 

mandrel bent is more expensive, and its harder to find shops that do it. as long as your doing something that doesn't have a lot of bends it shouldn't be too bad

 

Mandrel is always preferable because it maintains internal diameter, but press bending is fast and cheap. Personally I'd always go for mandrel bends, but I'm picky like that.

 

some1 suggested that if i was going 2.25 compression bent t
at i should go 2.5 to offset and crimps in the bends. any opinions?

 

Sounds about right.

 

what i did and i noticed a certain gain.. so i cant complain.

 

i was thinkin goin 2.5 to offset any crimps. wat muffler should i get w/2.5 inlet?

 

I read a paper that did the math on the flow characterisitics of mandrel and crimp bends, a while back. there was almost no difference between crimping and mandrel at angles of 45 deg or less. Greater than 45 starts to collapse the pipe.

For 90deg bends, crimping pretty much squeezes the pipe closed. If you take the heat shield off of your stock exhaust, you'll see what I'm talking about. The shop I buy my stuff from sells "U" mandrel bends and I cut the "U" in half to get my 90deg bend.

 

That does seem about right. Just thinking of a flexible straw at full extension vs one compressed and bent (I know the former isn't exactly a perfect example of a mandrel bend, but you get the point) you can see that there's very little difference until you start making more extreme bends. I still prefer mandrel bends to press bends whenever possible though. It's become a matter of principle with me, if not one of practicality.

 

You can easily jack the car up, and figure out what bends you need, and just buy the mandrels to suit .... if your shop doesnt sell the mandrel ones like Alchy's shop.

Mandrel of course flows best. I too prefer mandrel (even though the Mirage's exhaust was press bent but with a 3 inch exhaust, i wasnt too worried).

 

yeah could have gone 2.25 mandrel on my mivec lancer. But too pricey and went for 2.5 inch with compression bends. You would have marginal gains going for a mandrel system but really would be hard to notice. With my car being NA it likes a bit of back pressure so not really an issue to go to compression bends.

If your not worried about the extra cost then of course go for mandrel. I dont even have mandrel headers. I just got my custom set made out of slightly larger diameter.