MikegotaZ28

I just bought a 95 z28 M6 with 25k miles on it, and am looking to add some hp that won't effect my gas mileage or engine reliability (daily driver)


6.) How much hp did YOUR cat-back add? I see alot of people say the SLP is supposed to add 20-25 (I want to get a magnaflow) and some people believe a cat-back in general is only good for sound and 1-3 hp)
7.) Why do people think 2Pac isn't dead?
8.) I plan on installing headers with a full exhaust. About how much HP difference will that make from just throwing on a cat-back? Is it worth the extra money?
9.) Will number 8 cause any check engine lights to come on?
10.) Is it true that a CAI on an LT1 is one of the best mods since the stock intake is much more restrictive then the LS1?

If someone would even answer one of these questions, I'd greatly appreciate it. I've seriously been trolling this board for about 6 months and didn't even register until a few weeks ago, but lately the search function isn't quite working for me..so I'm sorry if I asked a ***-load of searchable questions.

Bones Z28

iTrader: (8)

https://ls1tech.com/forums/lt1-lt4-modifications/298077-ultimate-lt1-newbie-faq.html


that should answer quite a bit of your stuff. PS stickies are your friend.

seawolf06

iTrader: (8)

1. If you want to buy cams, get a Ford. A chevy cam swap can cost $500-800 depending on quality.
2. More horsepower always puts more stress on parts.
3. To have a cam installed is going to be a good amount since there is a lot of work involved.
4. Yes you will need a tune for a cam and usually your mpg goes down. If you're worried about that then you need to get another car.

MikegotaZ28

I don't think I need another car. Just because I don't want the MPG of a v-8 to go even lower on a car that is never going to touch a track, but will be drove every day doesn't mean I don't want my car.

97blackz28

iTrader: (6)

6. those numbers are extremes, i would say a good catback will add about 10 hp and makes the car sound 100x better IMO.
7.
8. LT headers will gain you close to 20 hp over just exhaust, so yes it is worth it
9. yes if you do LT's with ORY it will throw codes for the rear o2, if you run race headers that will eliminate AIR and EGR aswell that will throw codes too. it is best to have the PCM tuned for the LT's and then you will not have any issues.
10. A CAI is always good because you want the car to breathe as well as possible and intake and full exhaust will accomplish that goal.

ZONES89RS

iTrader: (25)

ALL THE BOLT ONS with a tune will be your best bet.

speed_demon24

iTrader: (6)

I gained 24rwhp with jethot longtubes and a mail order tune

Storms of War

1. Why does your list start at #6?
7. Because they're yambags, simply put.

Schweet97Z

iTrader: (35)

LOL!

2pac is dead?

Formula350

iTrader: (3)

2Pac is in my closet. I feed him crackers (saltines, just to **** him off even more) and on occasion I'll treat him to some Milk and Nilla Wafers

CAI, Headers, Cat Back and a tune will make you a happy camper w/o sacrificing much, if any, MPG. In theory, you should gain MPG since you're allowing the motor to breath better.

Formula_LT1

iTrader: (2)

Your gas mileage would probably increase with headers and intake mods. More air in, more air out. But, when someone tunes your car, they may add or take away fuel from certain areas of your fuel tables which would effect your MPG, but probably not alot. What KILLS gas mileage are things like big stalls, deep gears, cams, bigger cubed engines, ect.....Stuff that if your planning on keeping your car a DD you'll never get into messing with.

If you want some extra power but alot of driveablity, then go with like every aftermarket bolt on you can buy and get a GOOD tune. Don't buy a hypertech or something like that. Kick out a few $ for someone to dyno tune it and optimize what you've got to the fullest.

MikegotaZ28

So headers WILL cause my check engine light to come on?

The LT1 That Could

iTrader: (3)

Depending upon what style of header you go with, you may have to eliminate the air and EGR systems.

Actually, If you go with a Regular style LT header (non race style), nothing will be changed since you have an OBD1 car and no rear 02s.

If you go with a "Race Style" Header, you will be eliminating the AIR and EGR systems from the car. You can remove them completely and block off everything to clean up space in the engine bay and lose about 5 lbs, or you can leave it on and just block everything off. Its better to remove it all tho, as you don't REALLY need it anyways. This will cause the computer to think something is wrong, however it is a quick fix with any kind of tune, mail order or dyno.

Now if you go with a regular style header, with EGR and AIR Fittings, no tuning is NECESSARY, but it is probably best to get at least a mail order tune, to adjust for the increased amount of exhaust scavenging you're going to gain with the LTs. For mail order tunes, you have a few options. I don't know who is a sponsor in that section, I will not name any names, but if you want to PM me, I will give you a recommendation on who to go with!

Best of Luck with the new LOW MILEAGE LT1!! I didn't think there was an LT1 alive with less then 50K on the ticker! haha

MikegotaZ28

^ thanks you answered alot of my questions.

One more question..I know what headers are..but do I need to upsize the pipes running from the headers to the cat? Also, high flow cats I know they don't actually add any HP but do they increase sound?

The LT1 That Could

iTrader: (3)

I am not a fan of any type of catalytic converter. A cat only reduces flow and sound if you ask me. A high flow should should good tho thru LTs and a nice open flow muffler like a bullet, sweet thunder, or one chamber flow.

as for the change in size, most y-pipe collectors are 3" in diameter. You can mate up some 3" exhaust piping, or a 3" diameter cat......or do like i did and get a 3" to 2.5" adapter and run 2.5 exhaust out the back. I am running true duals tho....Either way it will sound great! 3" isn't too much, but it isn't necessarily needed to get a good flowing system.

really it all depends on the diameter on the cat you're gonna use, and the muffler you're gonna use....if they are 2.5, run 2.5 from the y-pipe back, if they are 3, run 3.....make sure that from the headers back size doesn't change from that point on. makes the scavenging effect more turbulent!

Bones Z28

iTrader: (8)

dude no offense but if your really concerned with gas mileage you bought the wrong car. Truthfully these cars aren't DD's to begin with, especially for those who have to deal with winter. Yes you can daily drive them but i don't see the logic in modding the car at all if it's a DD. At most i would do basic exhaust work (catback exhaust) and a cai that's about it for a DD.

97blackz28

iTrader: (6)

your right, totally overlooked that. sorry for the mis information.

GMRACER13

iTrader: (1)

My '95 M6 with approx. 125,000 miles on it made 293 h.p. and 330 tq. (on a DynoJet) with the following mods.

1) Crappy shorty headers (I think they were BBK) with the emissions tubes.
2) No cat.
3) Crappy Flowmaster 80 series muffler.
4) K&N CAI
5) Stupid airfoil gimmick in the throttlebody.

I didn't notice any difference in fuel consumption and I didn't touch the tune.

ZONES89RS

iTrader: (25)

No ****? Did you even have a tune? That is the HP i am look for in my 95, i lack a CAI but i got the rest + egr delete and i will be tuning soon.

The LT1 That Could

iTrader: (3)

not a problem, it almost always gets overlooked on the OBD1 cars....even my mechanic told me to run 02 sims back in the day, and i was like