I need help with my exhaust. My first exhaust setup was 2 1/2 inch pipe with Magnaflow muffler. That sucked so much because I couldn't feel any low end power (in fact, my car was accelerating like a 50HP car). Then I got 4-2-1 SR header, and installed it hoping it would recover lost low end torque. Although it gained little bit of low power, I still was not satisfied (on the contrary, my car really gained a lot of high end power!). Since my car was really LOUD and making ricey car like sound, I put 2 1/4 inch glasspack hoping that it would give me some back pressure and reduce the sound. However, it's now very quiet (not what I wanted) and I did not completely regain lost low end torque, yet.

So my question is, should I spend another $80 to install 2 1/4 inch exhaust pipe or should I spend that money plus few more bucks to get IM and TB bored out?

 

I would add more power. That would help you resolve the backpressure problem.
Go with the IM/BBTB and also some cams.

 

A properly tuned exhaust is critical to performance. This is where most of us screw up. I think going with the 2.25" pipe will improve the performance. If you still think your car is too quiet, have a shorter glasspack put in and point the louvers towards the front.

 

Thanx for inputs. I am going to fix my car first (someone hit my lovely Tibby ~_~) then will do other mods after body shop finish their work.

By the way, I have glass pack (or should I call it resonator) that has bunch of hanger holes that is attached to inner layer of the resonator... Is this really worse than the other type of glass pack?

 

2.25" all the way!!
2.5" is to big for N/A tib!!
Is't just my opignon

 

First off, I would have your car dyno'd. That way you can compare your dyno to other dyno's that have been done on N/A tibbies, and you can see if you really are missing torque on the low end, or if it is all in your head (or your butt dyno need's re-calibrating! *grin*).

Based on the dyno you have done, and comparing it to other dyno's that have been done, we can reccomend a course of action.

In general, a 2.5" exhaust helps the top end, at the expense of the low end. The 4-2-1 headers should have evened that out for you.

In general, a 2.25" or 2" exhaust helps the low end, at the expense of the top end.

The dyno will reveal the true situation. Rather than just throwing money at the problem, try to get a dyno done, and then base your next purchase/modificaton based off information and data.

BTW.. Louvered Glass packs should NEVER be use. If you do use one for some reason, the Louvers should point WITH the direction of flow, not against it. If you go with a Louvered core glass pack, increase the Inner Diameter of the louvered glasspack by .25" to .5" to compensate for the decrease in flow the louvers cause. Perforated core glass packs dampen sound just as well as Louvered core glasspacks, but do NOT dramatically increase the back pressure like louvered core glasspacks do.

Trying to "tune" the exhaust from the 'back' end is also the wrong way to go. You can't start at the muffler and move backwards towards the headers changing things to get the end result you want. You need to plan out what you want, and them modify starting at the headers and going back to obtain the results you want. The farther away from the header the backpressure/constriciton point is, the smaller the effect it will have. Mufflers rarely gain or lose more than 5 HP. However headers and mid pips can easily gain or lose 10 to 15 HP.

[ February 23, 2002: Message edited by: Random ]

 

Isn't Louvered glass pack metal clips suppose to face against air flow? Wouldn't it be pointless having louvered glass pack if the metal thing point to the direction of air flow?
I did not check in which direction the muffler shop installed mine... Do you think that they installed it against or same direction of air flow?

 

Bumpy

 

The louvers should go WITH the flow.

Turblulence causes backpressure. The louvers create less turbulence when pointed with the flow than against it. The cat should provide 75 to 80% of the backpressure you need, so the louvered core resonator/glasspack is NOT necessary. Definetly not pointed TOWARDS the engine. A perforated core unit would lower the sound levels and not increase back pressure.