I installed macs w/orp,and a flowmaster catback a couple of weeks ago the power increase was awesome but it has really bad rasp at 2000 rpm. I've heard that the macs cause the rasp and I've also heard it is the flowmaster,which one is it? I will consider bullets(exactly what location do you install them?) or maybe trying a different catback or both. What are some definite fixes?

[ November 23, 2001: Message edited by: JealouZ ]</p>

 

Well, since I have typed this out about 700 times already, i'll give you a link to read. Go to....


https://ls1tech.com/ubb/cgi-bin/ulti...c&f=1&t=000342


Read my reply about the Hooker catback. If you have any more questions feel free to email me.


JOsh

 

700 times wow that's alot! Thanks for the link.

 

Click on my custom exhaust and you will see where I installed my bullets.

http://xs-fx.com/raughammer/larrysample.htm

I'm afraid any exhaust system you uses is going to have this rasp with an offroad pipe. I get it even with the bullets but it is bearable.

 

so larry you still get a little rasp even with bullets and the hooker set up? Damian said the hooker cat-back will get rid of it?

[ November 23, 2001: Message edited by: JealouZ ]</p>

 

I went a different route!

I installed 2 cats in my ORP... but these cats flow better than most mufflers and almost as much as a straight pipe. Best of all I'm emissions legal too!

I went W/ C&L cats:
http://www.cnlperformance.com/cats.html

Here is a flow comparisions:
http://www.cnlperformance.com/graphics/25.jpg

And for being cats they are only 2.5" like $75-80 bucks each. They are quality pieces too... 5.0 Mustang guys have been running them for years!

It's a little more pricey option but, it makes that power and leaves ya street leagl too!

Here in NC I have an annual emissions test which would make swapping back and fourth a PITA.


Todd Rehr XLRATE

405.8 rwhp / 384.6 rwtq

'99 30th Anniversary TA WS6 (#1118)- M6: MTI lid, FRA, TB bypass, Ported and polished TB, Cooling Fan Switch,Power Cutout, K&N, 4:10s, MOBIL 1, Nitto DRs, Pro5.0 , SLP underive Pulley, MORE stage 2 CNC heads (2.08/1.60) & Cam (comp 216/220 - 525/532) & top end kit, Boxed LCAs, LS6 intake, Fernco Mod, Mac Headers and custom Y pipe (C&L high flow cats and FM collector), Ed Wright programming, MAFT, Star Stage 2 clutch, KnockOut Box.

[ November 23, 2001: Message edited by: TRehr ]</p>

 

Yes, this has been covered so many times before. You WILL indeed get rasp with any cat-back system or cutout if you run off-road pipes through them. Sorry, but I've even heard a Hooker that had the rasp in the mid rpms. Some exhaust will rasp more than others though. I personally think its a disgusting sound for our cars. But oh well, to each their own.

There may be a way to get rid of most of the rasp if bullets are used in the correct locations, but I would just recommend running cats to avoid that god awful sound. I think LS1's sound great with cats on. Maybe not as loud, but a much better sound.

Mike