I was just looking at my car and wondered since my tailpipes can't be more than 1.5" and there must be atleast 3 feet per side after it exits the single muffler. Does something like that make a difference?

 

The I-pipe will be more restricitve than the tailpipes themselves. You need to replace the whole cat-back to see any significant gains.

 

1.5" umm you better go measure. 2.25" and up is good.

 

Yeah, just measured, 1 3/4".

I just had a new catback put in and plan on doing headers in the future. I'm just wondering if the tailpipes are restrictive enough to warrant a larger replacement.

 

yeah ah 1 3/4 tail pipes are def way to small. go with 2.25 ~ 2.5

 

Don't bother changing the tail pipes. Two 1 3/4" tips have the same flow area as the stock 2.5" system (I am assuming 86 TPI cars were 2.5"). The whole system is a bottle neck but the tips are less restrictive than the I-pipe and muffler.

 

What part is the I pipe? I have a flowmaster muffler on it right now.

 

The I pipe is the long single pipe that runs along the undersie of the car. it connects your muffler to your cat. An aftermarket muffler is good but you see all your gains by going with a mandrel bent 3" pipe found in common cat-backs.

 

Damn, I just had new 2.5" pipe put in. That'll be the next thing I do then when I have headers done. Thanks!