This winter I wanted to open up both the intake and exaust on my L98 to get the most out of what L98 has to offer. I was strongly considering TPIS Big tubes and manifold with the plenium hogged out to match. TPIS said they would recommend a fuel pressure regulator and the 52mm Throttle body.

On the other end a set of long tube ceramic coated headers through the original cat and on back to a cat back set up that honestly I don't know what to choose. I have read every post I can find and its all up to who likes what. I do like quiet in my old age but do like to be able to have burble. I was thinking about the TPIS headers also.

What about the tune on this type of project? Yes new tune with top side, but no change with the exaust side?

I don't have the money to do both this year so I'm thinking go with the exaust side first and next winter the top side.

I could also do some roller rockers this year if that would help. I am putting on some new valve covers and would have them off anyway. What do you guys think? Thanks

I'll share my opinions and experience. One of the first mods I ever did on the car was my magnaflow 2.5 stainless steel catback. I needed new mufflers since they were rusted out. It was noticeably louder (precats already removed) and droned. I liked it, but yes it was loud. After the whole motor rebuild I added the headers, too. The sound is loud and aggressive from the outside, and ear drum popping loud from the inside. This winter I plan on redoing the exhaust.

From that perspective, I would not recommend this setup. If I had to start over, I would put a nice set of ceramic coated or stainless steel headers. I have painted ones, and the heat generated is too much. But they are already there, so oh well. In addition to the headers, I would add 2 high flow cats and mate them to a used LT1 exhaust system with stock mufflers. From what I can tell, it's a nice sound but bearable and does not drone inside.

I would do exhaust before intake. Personal preference, but I don't see the point in adding air "intake" into the motor without being able to expel it.

Also, by the time you are looking at big mouth base and big runners, you are getting into the same range as a used superram, or stealthram territory. I'd look at those as options, too. Not that the big base/tube setup is bad (I have it), just that there are other options out there.

The computer will compensate for the exhaust differences without much issue at all.

After the intake, talk to Mick about a tune.

Matthew

I would do the headers first. i personally have the TPIS headers on my 92 they were already installed when i bought the car. they are not coated i wish they were the paint is flaking off but what ever.

And if you want to keep drone down, get the Corsa system. I know, it's expensive, but that drone will kill you if you are like me and have sensative hearing.

I had elims... and the boom inside the cabin about killed me. Seriously. Hated them. Now, that was on and LT1... the stock L98 exhaust will deal better with elims, but blech.

I think you will see more performance gains from tackling the restrictive 305 intake base and runners.

Most people haven't tried enough different types of exhaust systems to recommend one over another. The best you can hope for is some feedback on what worked for them and what to do differently.

You really need to do both, so pick one...

That's what Matthew was suggesting.

Marcus, did you see the article that Tommy posted recently on the comparison of L98 intakes? Check it out, here.

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I like the looks of the stock TPI so will probably go with that TPIs system. What about roller rockers does it pay on a stock engine?

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I saw that and had run acrossed it awhile back. Very good stuff, again I wished they had used a stock L98 instead of the 383 but did note the gain of HP and torque on each different installment.

I imagine the results would be comparable to stock, but when you start with a stacked deck, it only gets more stacked, by an order of magnatude.

Then again, to get the best from those intakes, requires something be done to the engine.

What I have taken from doing a lot of study is that you should be able to get maybe 50 more horsepower and I don't know how much torque from opening up the top end and cleaning up the exaust. Plus it would be fun to do and is something that I think I can do on my own.

Like so many things, where do you start and where do you stop. It's all about time and money.

i agree that both can be opened up to make some great power .ron aka cuisenartevet sp .has ported a friends andrews intake with very nice results. you might contact him as to what he would charge you to set up an intake for you . on the exhaust you can either buy a system or have one fabed up yourself . it all boils down to what you want and how quiet you want it . i ended up fabbng my own by putting an xpipe in place of the resonator and using dyno max super turbos for a quiet yet basicly loss free exhaust .if you have a 92 or later you can do what i did for 86 summit narrow xpipe 210 for the dynomax mufflers and 150 for the muffler shop to put it on .

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Since you have the SD vs MAF system, I would ask Mick Stevens (MSeven) about the need for a tune with these changes. The very first thing he told me was to rely on your tune to accomplish fueling changes -- not an aftermarket fuel regulator. I agree. (It very well may be you don't need tuning with these alterations.)

The best and best sounding exhaust mod would be to convert to an LT1 exhaust system. That would include the manifolds. It's not TOO loud. Headers adds a lot more money. If you add them, that's O.K., but the exhaust seems to be the bigger issue. Personally, I like the sound of the bigger pipes with performance converters and simple glass packs. There's no drone, but it lets out the factory gurgle most people don't realize is already there.

For someone that doesn't port (or want to learn), the TPIS system is a good option -- expensive but good. It's the smooth mandrel-bent tubes that set it apart. OTOH, a FIRST intake is bigger and about the same price -- maybe less. Shop used to get the best buy here. I've seen both for sale at the CF. There's a FIRST right now.

The biggest improvement I've seen is 330rwhp and 400rwtq with head porting and a cam added to your plan. Everything was a TPIS part (headers, intake, etc...) Pull out the head/cam portion and you're probably not that far off hoping for 50hp gain. Torque will probably go up in the 20-25 range.

My personal thought was the valve springs and seals were getting old on a 20-yr-old car. (Notice light wisps of smoke on my 89 in the vid below. It only had 55k miles.) Because I opted to change those, I ended up considering the head porting (and ultimately bought aftermarket heads). Considering a top-end freshening would not be ill-advised IMO.

I went crazy -- thinking about adding a cam with head work, then considered what would happen to the bottom end. I ended up replacing the whole darn motor.

Performance upgrades/building is something you should do with careful thought about the condition of your motor and car. It's a very big investment that can get out-of-hand.

There's nothing wrong with improving your intake tubes and adding aftermarket converters/mufflers. It's the converters/mufflers that are most in question to me. They get old, fall apart and can clog up your exhaust. New ones flow better. It's that simple.

Start on the back-side. There's no question that's the weakest link.

FWIW, here's a vid of my stock 89 after said exhaust changes. The sidepipe have very little to do with the sound you hear. Performance converters and glass packs would sound the same.

That sounds good Greg! Where did you get those sidepipes? Do they drive you nuts going down the road? They look good! Nice wheels, I like the chrome on a dark color car.

I have the Flowmaster test pipe back exhaust and drone or no drone do not plan on changing it. However, when "The Mad Tuner" Ion Soltan was riding with me working on a tune, he said the Corsa brand LT1 style showed a significant improvement on the dyno. I found that hard to swallow, but that's what he said.

The Corsa is a straight through muffler. The inner tube is perforated, but that is for sound management. When you floor the Corsa, it blows right past that and makes a wonderful sound.

I have the Magnaflow catback/hi-flo cat and hedman headers. It's sounds good but does drone like hell inside the cabin. Plus you have to fab your own wye pipe which if you don't have a welder or access to one then that's an added expense. The exhaust did wake it up quite a bit per the sotp dyno.

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The SideEffects sidepipes were an aftermarket item made by Lawrence-Keech (www.powereffects.com) up until 2003. They've been discontinued. Occasionally, you can still find a set used. (orig price $1500)

They don't drive me crazy though once in awhile, you'll get a whiff of exhaust when driving with the windows down. Ground clearance isn't too bad. I just have to be cautious about situations where road bulges/bumps present a high-center. Steel jacking plates hang lower and take most of the brunt when bottoming out.

I like chrome with black too. Thanks for the compliment.

(BTW, I hope you got my drift about valve springs and 1.6 rockers. I didn't mention that specifically. You'd want new springs.)

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Do they have packing behind the perforations? Wasn't one of their "secrets" how they internally routed dual-outlet mufflers?

the corsa system only has 1 open pipe of the 2 tips on each muffler .thats how they manage the sound