Rep Power: 261

I running cat less right now and my new exhaust i guess is breaking in and i got alot of buildup on my bumper right now. how is this caused, how long is it gonna be like that and how can a fix it or solve the build up . Diffuser on the rear is wut im thinking i dunno

 
Rep Power: 396

By buildup you mean that black crap right? It wont ever go away, because you're cat inst collecting all the junk anymore. Also it happens when a car runs pig rich.

 
Rep Power: 261

I'm running a mechanical o2 sim right now and im getting 26mpg from 35mpg with stock cat and exhaust. Its not burning the bumper its just looks like a bunch of dust bunnies on the bumper right above the exhasut tip

 
Rep Power: 301

make sure ur car is not running to rich without that cat?

 
Rep Power: 285

it will probably always do it without a cat. I know my car was always covered in carbon buildup when i had no cat.

 
Rep Power: 261

wut about a diffuser (plastic trim to go over the exhaust tip area on the bumper) usually black or carbon fiber.. how does that work/help the situation?

 
Rep Power: 285

it will still get some buildup on it.

if you want, justy wipe it off every day. Just takes a second

 
Rep Power: 261

wuts better...? cat or no cat for a turboed Vic. Cuz thats wut im piecing together right now, and when I'm where i wanna be at financially im gonna build my k24a2/k20a2 franken up and drop it in, boost till it blows/dies (low boost i.e.). U guys have been great help so far

 
Rep Power: 285

no cat.

turbos work best with the least amount of restriction possible

 
Rep Power: 261

you guys will get repped mang, im just gonna try to keep the ish clean i guess. lol i m lazy mang

 
Rep Power: 396

Yeah. BTW actually under difussors are not made for whats the problem is here. They are to decrese the amount of drag and air turbulence that happens underneath your car and rear bumper. Without your cat you WILL have to clean it alot to keep it nice.