I'm looking for a little advice on performance mods... I'm starting with a 91 Coupe L98 6spd.whose only mod is a pair of Flowmaster Mufflers. I'm Looking to add long tube headers and 1.6 roller rockers as soon as some snow hits the ground and I have an excuse to take it off the road. Is some sort of air filter system other than the stock one advisable? Also,after all this is done, will I feel a noticeable difference in the "seat of my pants" or just in my wallet?
Thanks for your help...
Mike

 

K&N and cutlid? Is that what your asking about the intake one. I dont know how free flowing YOUR MODELS exaust is. Dont know what emissions are either. That plays a big factor in what you can/cant do.

 

Yes, increasing the exhaust flow and allowing more clearance on the valves is a good mod. Stiffer valve springs are recommeded as well. The K&N with the cut lid seems to be the best and cheapest way to increase air flow. Adding a heated O2 sensor is recommeded with the headers.

Good luck.

 

Also go with a hi-flow main cat to fully benefit from exhaust mods. Be sure the FL headers are ceramic coated in/out for best heat dissipation and maximum exhaust gas flow.

I recommend the Comp Cams ProMagnum RRs with #981 springs. It would be a good time to replace the factory valve seals and get new forged keepers too. Eliminate the oil shedders from atop the stock valve springs to lighten the valve train a little.

The K&N filter w/ cut lid is a good mod for 10chp gain.

Remove the "frisbee" from the water pump pulley, story on my site.

Install a 160deg F T-stat & fan switch. I drive one year around and easily pass the OH E-check sniffer in Feb.

Cut back a set of stock AC Delco spark plugs for a light free power gain.

Install an AFPR so you can bump fuel pressure to blend with the increased air flow at WOT that you are introducing.

With the above mods you should be able to bump peak power to the 300chp range and still have that great L98 low end torque.

If you would like it to pull better at top RPM, try the siamese intake base mod. Dyno results are on my site; I will send you pics of my siamese base if you drop me an email on the topic.

BTW, in what part of SE NY are you located; I'm near Blauvelt.

 

Thanks for all the info...I'm trying to figure out what it all means and come up with a logical plan of attack. And by the way 65Z01, I'm just a few miles north of you up Western Highway! I'll check your site when I have more time. Thanks again guys