Just recently had a flowmaster 40 series SI/DO put on my truck. Pipe size is 2.5" from the cat back. after everything that i read about the 40 series, it seemed like it would be too loud, but its too quiet. you can barely hear it at idle and only really hear it when u get on it hard. right now i dont have tips, but im planning on putting 3"x18" tips on it. i was wondering if a high flow cat would liven this thing up a little bit. btw the truck is a 96 f150 with 302.

 

i am having similar problems if you read my post, thinking about removing both of my cats... on my 93...

 

High flow cat will liven it up a bit so I am told, I'm bad for going at my exaust armed with a grinder so I never have cats anyway.

 

Do you have the "original" 40 series? There's also the "delta" 40 series which is a little quieter at idle and loud when you give it some throttle. I have the original 40 series and at idle I can hear and feel the rumble. A high flow cat may not give you an increase with noise but will help the engine get rid of exhaust faster.

Warr

 

removed one of my cats, sounds better noticeably, probly get rid of the other some time soon.

 

Scottya4, you should run at least one high flow cat if your vehicle is registered and have state inspection. Don't want to get caught, EPA fines are pretty hefty.

Warr

 

up in canada. most i know dont have any cats.

 

Sorry, I wasn't aware you were in Canada.

Warr

 

yea i got the original 40 series, part #'s match up. next up is tips and a high flow cat

 

389-430402 thats the 40 series i have on my truck. its in the link below. you will have to scroll down to find it under gm replacements mufflers. its the original 40 series right?

http://www.jegs.com/cgi-bin/ncommerc...08&prmenbr=361

anyway i run this si/do dumped under the bed with stock cats on my 88 f150 5.8L. it really doesn't seem very loud, but it sets off car alarms so who could say lol. firefighter i had the same prob as you , i had mine piped straight out the back with tips and for a while without tips. wasn't very loud or impressive at all. dumped sounds much better. louder too. though its really not all that loud IMO. its actually about sounds about right IMO.

edit: you have to click another link on the next page to get to it. why does FTE do this now? it wasn't like this last time i came here. its rather annoying and pointless.

 

apparently they "have their reasons" but i agree with modru