If I already have a catback system an I'm getting a downpipe do I need a midpipe? I'm just wondering what the midpipe does? Does it add a lot of power like the downpipe? And does anybody have any suggestions on a downpipe? I was thinking either pettit or HKS. And one more question does anyone know how many horse a downpipe adds. One that is not street legal (replaces cat)_

93' silver RX-7

 

You don't need to get a midpipe when you get a downpipe, but you will get a lot more power from having a straight pipe with no cats. But if you do get a midpipe you will need to get an ecu upgrade if you want to be safe and not lean out.

As far as downpipes go, most of them are about the same, provided they are made of 304 stainless steel and are mandrel bent and with a 3" diameter. If I were you, I'd go with the Pettit one over HKS because the HKS one will be overpriced, as with most of their products. Even the Bonez one that RP sells is a good choice.

 

The M2 pipe has the cleanest bends I've seen - the HKS pipe uses the same casting as the stock pre-cat at the turbo end (smaller opening)and is only 2.75" not 3" like the others