whould it hurt the car if i ran it with the straight mid pipe and catback but stock dp

 

You may need some kind of boost controller, or upgrade your ecu to a Pettit, Pfc, or the M2 (with boost controller). Usually people will swap out the first cat for a downpipe, then the mp. Perform your upgrades properly and your car will reward you.

Typically, the order of BPU mods would be:
1. catback/air box
2. DP
3. ECU or boost controller
4. I.C.
5. MP

 

I'd suggest doing the dp before the mp for reliability reasons.

 

Why would you want to keep the stock dp, and change the mp and cat-back? I mean, that's like using a condom with holes in it. Not a wise decision.

 

Assuming that you have adequate boost control or ECU, it's doubtful it would "hurt" the car.
You probably wouldn't see any boost creep with the pre-cat in there, but you probably still see increased boost if not controlled..

HOWEVER, it certainly isn't the best way to go. Removing that hunk of metal from the engine bay is arguably one of the best reliability mods you can perform, simply for the heat reduction in the enginebay.

I'd say, go with what's been proven to work. Leave the stock cat, and get a downpipe.

 

x2

 

x3

One of the main reasons for removing the pre-cat is to get rid of a major heat source near the engine.