[aldo_cella]

Should I drop the cash on the total system if the only other engine mod's will be air cleaner and chip on my '02 S4?

 

[Guest]

while there are gains to be had compared to just slip-ons, i wouldn't bother unless you can get the full system for a good deal.
why? i think to really make a full system (larger-diameter header) worth while, you'd want to get a valve-job on the cylinder heads. the idea being to get as much flow in the cylinder heads as the exhaust can handle.

there are of course benefits to going with a full system with just the airbox mod + fuel injection tuning. you save a bunch of weight (but you save a bunch of weight with slip-ons as well), you get better CORNERING CLEARANCE!!, and you get a bit more power than with just slip-ons.

but a full system COSTS a bunch more. a BUNCH more than just slip-ons.

personally, i got my hands on a header from an st4 which is 45mm's compared to the s4's stock 40mm's. fabbed up some mufflers using 50mm tubing for the slip-fit, some 748 cans for the muffler bodies, and 52mm perf'd tubing for the cores. flows very nicely, sounds really mean, and didn't cost all that much to make. the only problem is that if i go "boom" badly enough to destroy one of the cans, it's a bit of a project to make another.

 

[chris]

i think to really make a full system (larger-diameter header) worth while, you'd want to get a valve-job on the cylinder heads. the idea being to get as much flow in the cylinder heads as the exhaust can handle.

Hi Strati,

A "valve job" is when you renew the valve-to-seat "joint" by refacing them. A valve job is only to make the valve and seat to original specification. This does nothing for power. Then you can get a 5 angle valve job, which does incrementally improve flow, but it is reserved for racers who do a whole host of small changes hoping for an overall improvement.

What you probably mean is head porting and/or the installation of larger valves and larger valve seats. This is a task to be trusted to tuners with verifiable and proven results.

Chris

 

[Guest]

What you probably mean is head porting and/or the installation of larger valves and larger valve seats. This is a task to be trusted to tuners with verifiable and proven results.

Chris

yes sir, that's exactly what i meant. larger vavles/seats for more flow through the head to match the capacity of the larger headers. thanks for clarifying chris. used the wrong term cuz i'm too lazy to type out the correct info